(I now own an MPC3000 myself and will eventually post some comments myself)
He's a compilation from Simon Canberra (Australia):
Not sure about the groove of the sequencers, but here are some differences I put together for the Akai mailing list...
MPC60 only has 750KB memory, expandable to 1.5MB.
MPC2000 and 3000 expand up to 32MB
MPC60 is 12bit/low sampling rate, lofi sound
MPC2000 and 3000 are 16bit/44.1KHz, hifi sound
MPC60 and 3000 have 2 MIDI In and 4 MIDI out
MPC2000 has 2 MIDI In and 2 MIDI out
MPC60 and 3000 have built in SMPTE-pulse96-FSK24-1/4 click sync
MPC2000 has SMPTE as an option
MPC3000 has built in extra 8 outputs and digital in
MPC2000 has optional extra outputs and digital in/out
MPC60 and 3000 have good strong build quality/strength
MPC2000 has poorer build quality/strength
MPC60 and 3000 are all older styled text based screens
MPC2000 has more modern graphic waveform display/editing/menus
MPC2000 has optional onboard effects, 60 and 3000 don't
MPC2000 has track mute screen, 60 and 3000 don't
MPC3000 has optional VGA display output
MPC60 and 3000 have 2 footswitch inputs,
MPC2000 needs MIDI footswitch
MPC60 and 3000 sequencers may have different 'feel' with swing etc. to 2000 (not sure though) truth here
MPC60 and 3000 has 'echo' effects send/return
MPC3000 has s3000 sampling engine/filters
MPC2000 has s2000 sampling engine/filters
MPC60 has (?, maybe s900) sampling engine/(filters?)
MPC2000 and 3000 have SCSI as standard
MPC60 has SCSI as a third-party option
The MPC2000 has a lot more features than the MPC60 or MPC3000. The MPC3000 is sort of half way between the MPC60 and MPC2000, it has the expanded memory of the MPC2000, with the older style screens and features of the MPC60. It all depends on what features you consider important in your MPC. The 60 is very limited memory wise, so may be better suited to creating beats from single hits, rather than using full bar loops like some do with the 2000. The 60 has the 12bit lofi sound that some prefer over the 3000/2000 16bit CD quality sound. If you want more than two MIDI outs you may prefer the MPC60 or 3000. If you simply want the 'old school' beats feel then you would prefer the MPC60 or 3000.
The preference for the MPC60 may be a preference for the 'old school' way of doing things, but could also have to do with the lofi 12bit sound and maybe the feel of the sequencer and it's swing. You should try one out before buying it.