I have an 80GB without PS2 backwards compatibility, that I've had since November 2008. I really wanted one with BC (mostly to upconvert PS2 games to HD), but I couldn't beat the price I got on my console. Plus the old BC ones are having hardware troubles now with the YLOD, so I'm kinda glad I don't have one.
250GB Slim. As many demos as I download, it was well worth the extra. I only have half of my HDD space left! : p
I have a 250GB slim version. I had GAME care (if it was hardware or accidental damage, could get a new one of that version) and my 80GB FAT broke. Brought it in and they said they didn't have any 80GB FAT's, so they gave me a brand new 250 GB slim. I was happy!
40GB PlayStation. My dad got it for the family for Christmas in 2007 and if he'd told us about it beforehand, I would have been up for pitching in extra to get the 60GB backwards-compatible model since that was still for sale then. :'( It's served me well, for the most part, except now with the Welcome Back program and trying to download a full game on it, I had to go in and delete tons of stuff just to get Infamous to fit... and if I want to download anything else, I'm gonna have to delete that. xD;
I have a 250gig Slim that I got as a Killzone 3 bundle. I also have a 80gig Fat that I got as an MGS4 bundle. The 80gig plays PS2 games but I think it's emulation (I think that's what it's called). It doesn't play all PS2 games so it's not like the old 40gig PS3s.