The one that I have consistently enjoyed over the years is Ratchet & Clank. None of the others really come close for me.

agreed and for $30 it was a steal.  I love Sony being willing to sell games like Sly 4, Puppeteer, and the new R&C for $40 and that for $30

Uncharted/Ratchet and Clank.

I absolutely loved Tomba!, but 2 was not as good for me. I think it was 3d, and I preferred it as a 2d game. Still both of them are some of my all time favourite games. It's nice seeing I'm not the only one who liked them.

I can't say i've had much experience with 1st party Sony games (I'll have to get on it), i'd say when I was younger I had a blast with Little Big Planet, so it'd probably be that

That's a tough one. My favorite studio is Team Ico, so Ico and SoTC would certainly be up there.

As far as series go, I'd probably give the edge to Infamous or Wipeout. Uncharted has been mostly excellent and The Last of Us is outstanding, too (although I hope it doesn't become a series).

Killzone has been wildly inconsistent, unfortunately. Ratchet & Clank and God of War, conversely, have been consistently great. I adore the original Jak but it was downhill after that (although Daxter on PSP was a nice return to form). Folklore is a solid IP that didn't get enough love. And Gravity Rush has a lot of potential. Patapon and Sly Cooper deserve honorable mention as well.

Does Demon's Souls count? If so, that would be tops also.

Hard to pick, but I went with Ratchet and Clank. Fun, reliable, smart, hilarious. Back on the day, it was genius to combine all of this with RPG elements and wacky weapons. Sure, the series has seen better days, and other games have built off of its premise. But they're a classic duo. I get stoked every time they announce a new game.

Hard to choose but I'd probably have to pick God of War.

I'm more oldschool, so Crash Bandicoot and Spyro the Dragon.

Spyro the Dragon, but it isn't Sony's.

So I have to pick Infamous and Uncharted.