new guy: which console to buy

Hey all, buying my 1st ps3. I would appreciate suggestions about which to buy.

I was looking at the 500gb Assassins Creed bundle, but im not thrilled about the new design( mostly the sliding tray) from what i gather there is no real difference between the slim and ultra slim pertaining to performance.

I can get either a refurb or used slim 2k series which could possibly be hackable. Since i like to hack/mod everything, this would be great as i find loading discs to be tedious :D

I do like the idea of having a new system with 500gb storage tho...

So whadya think, go with a new bigger, but cheaper build ultra slim, or a used slim?

Any helpful feedback is welcomed
Thanks -Z :)