PS3 (late 2007): For MGS4 and on the assumption FFXIII would be exclusive.

PSP: Crisis Core

If I bought a 360 it would be for Alan Wake and Lost Odyssey

Xbox 360 -

Mainly Gears of War, Halo 3, Oblivion, and the promise of Rare support, which hasn't really been much, but I didn't know that at the time.

Wii -

To be honest, I probably would have bought the console as long as Nintendo supported it. But if I had to pick the standout games, it would be Wii Sports, Mario Kart Wii, Mario Galaxy, SSBB

DS -

Same as Wii, Nintendo handhelds have never let me down. The games that initially intrieged me though would be Mario 64 DS, Mario Kart DS, Animal Crossing, Brain Age

I bought Wii on release day because of Zelda

I bought xbox360 on release day because of Enchanted Arm

I bought PS3 on release day because of Playstation brand and play FF12 on it

I bought PSP because of the hype

I bought DS for Brain Training

PS3 (Bought in 2006)
I bought the PS3 because is was the next PlayStation. I bought it at launch because the launch of the PS3 here in Australia was 1 Day before my birthday :D. The PERFECT Birthday Gift really :D!!!

But since I knew MGS4 existed in 2005 and I was soooo hyped for it, technically you could say that I bought a PS3 because of MGS4 and it has not let me down :D! And I bought the PS3 because of future Gran Turismo, Final Fantasy, God of War, Ratchet and Clank, Devil May Cry, etc games that I knew were gonna be released sometime.

PSP (Bought in 2009)
I bought the PSP because of Dissidia Final Fantasy. I really wanted the Crisis Core Bundle but during that time, I was really busy with school and all so really I didn't have the time to buy or play the PSP. And then I passed up on the God of War Chains of Olympus Bundle as well due to the same reason and then when news broke out that there would be a Dissidia PSP Bundle, I had to get it so that's how I got my PSP.

Nintendo DS (Bought in 2005) Nintendo DS Lite (Bought in 2007)
I bought the DS because of Mario and Pokemon games.

Nintendo Wii (Bought in 2008)
I bought the Wii because of Super Mario Galaxy, Super Smash Bros Brawl and Wii Sports. One disappointed me but the other two (especially Brawl), was just fantastic.

DS: Meteos, Another Code, Hotel Dusk
360: Beautiful Katamari, Dead Rising, Wartech Senko no Ronde, Soul Calibur IV*
Wii: See sig.

* I found out that Masumi Asano offers voice work for custom characters, and there's Maid DLC. Fighting with Izumi Sawatari fuck yeah

EDIT: Removed pre-generation fluff ⍨

PS3: At the time for Heavenly Sword, Resistance and Uncharted. Was more for the promise of MGS4, Killzone 2, Heavy Rain, GT5 and FFXIII though.

Wii: Wii Sports and Zelda

360: Was a present so it doesn't really work, but mainly for Gears of War and Halo Wars (bit of an Ensemble fan).

PSP: Crisis Core

PC: I always buy/have a PC but this gen: Oblivion, Fallout 3, Crysis, Half-Life 2 Episodes, Portal, AoE3, Mount and Blade, The Witcher, Neverwinter Nights 2, Dragon Age: Origins, Mass Effect 1 & 2, CoD4, numerous mods and for the promise of Starcraft 2 and Deus Ex 3.

Did you think it was worth it when Enchanted Arms came out? 

PS3 - mgs4 (disppointed but decent game), ffxiii (loved it bt went multiplat so agen waste of money), kingdom hearts 3 (ok dnt call me stupid)

ps3 was a waste ov money bt then i played games like lbp, uncharted, hevenly sword and lots ov first party ps3.

now ps3 is my favrite but not because of th games i got it for.

_

xbox 360 - elder scrolls oblivion (very disappointd), halo 3 (liked it), gears of war (liked it), mass effect 1 (loved it), star ocean 4 (i'd say worth it)

xbox was worth it in end, but now i dnt like it tht much even though splinter cell is amazing.

Wii: Brawl, adventure games, Wii Fit, motion controls/pointer

360: Dragon's Age, Mass Effect

I got my Wii for mario Kart and my 360 for Halo 3.