Personally Id love to have
a yamaha cs6x. Then Id expand it with 2 anx1 synth boards adding the analog emulation engine into the fray. And that famous korg analog modeling is actually using technology licenced from yamaha bear in mind.
There's also
the emu mo'phatt and extreme lead modules. And recently emu has released versions of both in a workstation with a built in sequencer and drum pads + lotsa knobs.
For samplers, if your doing rhythms youd want multiple outputs, or killer built in efx. I just bought
an emu esi 2000, wich was only $499. It can hold 128 megs of ram with 64 note polyphany. Now I need to fill it with ram and get the expansion board wich will give me built in efx, 10 outputs and spdif digital outs. If I was to do it over I think Id save for an emu e5000, or
akai s5000. The e5000 uses emus new os, as do all their moduldes, wich means sample disks for the older esi os(like I have) arent as plentiful(though there are quite a few from emu). Maybe youd want
an akai s3000, you can fined one used at
www.digibid.com. The s5000 looks much better though.
Then of course theres the asrx. It has a BAD reputation because of a buggy os and buggy scsi transfer coupled with a cpu too weak for its sequencer to properly function.
The mpc 2000 is cool for its sequencer, but its sampler is kind of weak. If your going for just the sampler even an esi 2000 is much better.
Theres also the korg electribes. Theres all those roland modules. Korg triton and trinity ...