Here is my list.
1. Genesis - I hemmed and hawed for a long time before finally settling on the Genesis. It basically comes down to it's library of crazy unique games and lots of arcade action. I'm a huge shmup fan and the Genesis is home to some of the best shooters of all time. Over the years I always come back to this system and I have so much fun when doing so. Truxton, Fire Shark, Mutant League Football, Shining Force, Landstalker, Ms Pac Man, Sonic, Splatterhouse, ToeJam n' Earl, Shinobi, and more. I love my Genny!
2. NES - There are so many classics for this system it continues to surprise me even today. I'm still tracking down games I've never heard of! As I've gotten older I've come to appreciate its pick up and play potential. You can hit the power button and play Stage 1 in less than 15 seconds. It's such a breathe of fresh air compared to modern gaming....for me anyways. The library is chock full of platformers, shooters, RPGs, sports games, puzzles game, arcade ports...anything you could possibly want. It's funny...as a child always you to dream about the advances in videogames and how good the graphics would get. Now that it's all happened...I'd rather play my NES.
3. SNES - Big Shocker right? Some of the greatest games of all time were created for this system. Super Metroid, A Link to the Past, Super Mario World, Final Fantasy III (VI), Chrono Trigger, Secret of Mana...the SNES has plenty of long ass games to keep you busy. That's part of what drags it down for me though. I don't always want to invest the time to play these lengthy adventures. It still has great shooters, beat em ups, fighters, sports games and more though.
4. Wii - I think this belongs up here. This is where my list got hard. The Wii has a fantastic library of 1st AND 3rd party games. Games like Super Mario Galaxy 1/2, Twilight Princess, Epic Yarn, Smash Bros, Mario Kart and others are top notch games from Nintendo. Then you have stuff like No More Heroes 1/2, Little King Story, A Boy and his Blob, Zack and Wiki, Muramasa, House of the Dead, Sonic Colors etc...it's just a great library of games. Plus it can play Gamecube games as well. So yeah that's a plus. Two fer 1!!!!!!
5. PS3 - Ugh...this was hard. I came very close to putting the Dreamcast here. 5-6 years ago the Dreamcast was my favorite system of all time. It's fallen off quite a bit though (I don't even keep one hooked up anymore). I chose the PS3 because the system quietly had one of the best lineup of games in a long time. The Uncharted games were amazing, I love 3D Dot Game Heroes, Twisted Metal, Heavenly Sword, Dragon's Crown, Folklore, Metal Gear Solid 4 and more. The fact that all PS3's can play upconverted PS1 games gives it the potential for a huge library of games. I play PS1 games on it almost more than PS3 games. Again, 2 for 1. It's smart for companies to put backwards compatibility into new systems. This thing lets me play anything from Joust and Sonic 2 to Final Fantasy IX and Diablo III comfortably on my couch while set up on a big screen HD TV. Yeah it's earned this number 5 spot.
So what's your list look like? It can just be a list...don't need to go into detail...but feel free if you want to!
The 3DS, as well, to some extant, however handheld gaming is always a full rung down the ladder for me. I like and appreciate handheld gaming, but it never seems to have the staying power of console gaming to me. I tend to really be invloved in a hadheld when I first buy one, and then slow down unless a must have game comes out. My console gaming is more steady.
I am also a big fan of the NES and the Wii. I also think the GC has a very fun library, a really fun console to collect for.
I would put the N64 and SNES much further down the list. The N64 is a neat console but has a flawed control pad and many primitatice games. The SNES has too many generic games, and games that were not as fun as their NES forefathers, and games that were 3D to soon before their time.
I like Dreamcast a little, but the console is probably a little too Japanese flavored for me. Some games that are big hits for others are misses for me....
Mega Drive/ Genesis: Sega at their best, their big IP's consistently great. Sonic, Shinobi, Golden Axe, Streets of Rage, Phantasy Star. Terrific third party games (back when EA were good). Fast paced, balanced arcade style action. God I miss you Sega !
Atari ST - Had little impact with you guys over the pond but was massive here in Europe (although the Amiga eventually beat it). Nostalgia plays a big part in this as this was my main system during my teens. Deep games, arcade ports, massive game library awesome demo/cracker scene. And I loved it's AY chip tunes.
Game Boy - My introduction to portable gaming, I didn't have a big game library as I only played it as a portable machine but was impressed by its console quality gameplay.
Turbografx 16/CD- hugely underrated console and so unique that I just can't help but love it. I love the design and the old school games that only ever seemed to appear on this console. It was also the first U.S. (not sure if outside the U.S. but I believe it is too) CD based console. Importing games for the console also opens up a huge library of games.
Dreamcast- A wonderful console with a huge assortment of games, many of which have an arcade feel. Sega really put down all the stops to try and make this console successful and it shows. It has many games that no other console has and has a wonderful design.
PS2- One of the best consoles of all time and my favorite console from 2 generations ago. It is also pretty cheap to collect for.
SNES- Many classic titles and beautiful 2D graphics (usually).
Genesis- The rivalry between Nintendo and Sega really pushed out some amazing games for both consoles. I love both of them.
4. NES - The all-time champ. Drifted from it the last few years, but still awesome. Sooooo many games. When I was younger I enjoyed the epic adventure-type games like Zelda & Metroid the most. Nowadays I tend to enjoy the arcade-type games more like Elevator Action (perhaps favorite NES game) & Galaga.
3. PSP - Hot Shots Golf, Tactics Ogre, multiple collections like SNK, Capcom & Taito. Limited selection of movies, but still enjoy watching something like Toxic Avenger on a portable device.
2. Gamecube with Gameboy Player - Resident Evil 4, GBA games and more.
1. Xbox 360 - Fallout 3 & New Vegas, Sonic's Ultimate Collection, Bioshock
I haven't had a Turbo Grafx 16 in years, but if I ever manage to get one it could make the list for nostalgia factor alone. PS2 would've made the list if I weren't on my FIFTH one, because four of them have died. Intellevision was my first love, but I no longer have one & wonder how much I'd really enjoy it at this point. Wii could probably make the list as well. Wish they had expanded more on Sports & Sports Resort.
PS3 - older model that plays PS1 & PS2 games, play online without extra fees, also plays Blu-rays & DVDs.
NES- lots of classic games like Contra, Donkey Kong, Mario bros., & etc.
Sega Genesis- nice 6-button controllers & lots of fun games like Super Street Fighter 2, Mortal Kombat, NBA Jam, & etc.
Colecovision- lots of old arcade ports like Donkey Kong, Lady Bug, Mr. Do!, Pepper II, Carnival, Frenzy, and etc.
Atari 7800- backwards compatible with Atari 2600, which has a large library. Games like Adventure, Asteroids, Centipede, Space Invaders, Phoenix, & etc. There are also a lot of great home brews.
2). Dreamcast. This system has one of my all-time favorite games in Shenmue, but also a wealth of amazing 2D/3D fighters, arcade-style games (Crazy Taxi), quality rpg's, insanely fun sports titles, fun oddities (Typing of the Dead)! The fact that the system only had a shelf life of about a year-and-a-half makes it even more impressive!
3). NES. This is where gaming was truly born for me. I had an Atari 2600 beforehand, but this was my digital best friend growing up.
4). SNES: if the nes took me through childhood, the snes took me into my teenage years with style! So many amazing games, and the peak of classic Nintendo (in my opinion).
5). PS1: I know that the games have aged poorly, but I saw this as being the system that I wanted the N64 to be. The controller was comfortable, there was always a flood of quality games coming down the pipeline, and.....going from 2D to 3D was amazing, at the time!
You guys, I swear this isn't me with another name.
You, sir, have incredible taste in gaming machines.
I guess, right now, it's:
3DS: The 3DS and DS combined libraries are insanely good. Right now I've rediscovered NSMB DS, which I really didn't appriciate at the time, and can't get enough of right now. I also recently finished off Nanostray, which is also incredible. Plus, best Animal Crossing game ever.
Wii U: The eShop and physical release libraries really are incredible.
Wii: I could have put this under Wii U, except the backwards compatability with GC is very important. Incredible library. Very deep. Very fun. A must own system.
Genesis: I love this system. I can't go into the number of ways the library is incredible. The controllers (6 button especially) are perfect. I am going to order the thing to make it play Master System games now too, since Stoneage Gamer makes new ones for cheap (that's a pro-tip for anyone reading all of this).
7800: 2600 + some incredible arcade ports + some strange, one of a kind games + an incredible homebrew scene = most under-rated system in the world.