Here is shizzy's 2 cents:
PSP 1000:
THE GOOD:
- Capable of full cfw installation.
- Feels more sturdy and better built than other PSP models
- Capable of creating Pandora Battery
- Capable of 1.50 kernel installation for M33 users
THE BAD:
- Feels too heavy and bulky compared to the other PSP models
- The lcd screen is the dullest of any PSP model
- Can not charge through the USB port
- No TV out mode (you can buy a heavy, bulky attachment to display it on your TV)
- major issues have been reported with PSP 1000 compatibility with PhotoFast 5400 adapters
- The lcd screen does have slight "Ghosting" issues during rapid onscreen movement
THE UGLY:
- The D-pad is the worst of all PSP models. It feels sunk in, mushy, and non responsive compared to the other PSP models... Diagonal movement feels impossible to pull off during intense gaming sessions.
PSP 2000:
THE GOOD:
- Capable of full cfw installation (* as long as your mobo is TA-088v2 or earlier)
- 64 mb of ram (compared to PSP 1000's 32 mb of ram)
- Much lighter than the PSP 1000 (makes longer gaming sessions more bearable)
- you can charge your battery through your usb port
- The D-Pad is erect and responsive
- Capable of making a Pandora Battery (* as long as your mobo is TA-088v2 or earlier)
- Has TV out capabilities
- brighter screen than PSP 1000
THE BAD:
- the stock battery is actually a little smaller than the PSP 1000 stock battery
- some people think the lighter feel makes it feel cheap
- The lcd screen does have slight "Ghosting" issues during rapid onscreen movement
THE UGLY:
- If your PSP SLIM has a mobo that is TA-088v3 or later, you can not use a Pandora Battery on it, and cfw can not be fully installed to flash
PSP 3000:
THE GOOD:
- Better LCD screen (brightness & colors) than any previous PSP. Also SONY seemed to have fixed the "ghosting" issue of previous models
- built in microphone
- has all other advantages over PSP 1000 that PSP 2000 does. (except full cfw installation)
- may not be worth mentioning, but some people like the look of the thinner metal ring on the UMD door...
THE BAD:
- The LCD screen has scanline issues
- *You can not fully install cfw to nand on these units. Instead you must use HEN to basically emulate cfw. In other words, your cfw is can only be applied "temporarily" on PSP 3000
THE UGLY: *Unless your OFW is version 5.03 or lower, you can not use cfw at all on these units !!
PSP Go!:
THE GOOD:
- schmexy slide screen
- bluetooth compatible
- you can use your PS3 paddle to play it
- 16 GB internal memory
- you can tether it to a bluetooth cellphone for internet connection anywhere
THE BAD:
- no UMD drive (SONY apparently wants to sell you the same games twice)
- smaller screen
- requires all new new proprietary peripherals (usb cords, M2 memory sticks, tv out cords, ect...)
- since you can only buy digital copies of games, you can never trade them in
- The battery unit is not removable/replaceable
- SONY still didn't add a second analog stick... grrrrrrrrrrrrr.....
THE UGLY:
- You can not install or enjoy any homebrew or custom firmware on these units!! (unless you are on Team Typhoon or another elitist hacking team who refuses to share...)
So there you have it. (Phew - that was more typing than I first thought it would be :P)
Of all the PSP models available, if I had to pick one to be the best, then it would be PSP 2000.