No matter which model you get, do replace the internal hard drive with a SATA SSD. Virtually any SSD will do since the bus speed is the limiting factor on PS3

Later revisions of fat models dropped PS2 hardware components and should be cheaper to obtain. Depending on which PS2 games you want to run in addition to PS3, the built-in PS2 emulator can still be good enough on these. There is a game compatibility list somewhere for PS2 emulation on CFW.