I'm quite the fan of Korg multis, especially green series from the 90s.
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It may just be because I know them very well and started using them very early in my playing.
To me they have a perfect balance. Very easy to tweak onstage, reliable, foolproof while offering a vast array of tones you can't find anywhere else.
The newer series aren't as good IMHO.
The AX-10B is simply worthless.
AX3 and 5B while doing a good job don't sound as "pro" as older series. It's hard to get an ample, steady tone without a lot of tweaking. Editing is a PITA with too much data on a 2 digit screen.
The AX-3000B has a fantastic user-friendly interface with a lot of nice functions. You can use the expression pedal in a lot of innovative ways, coupled with the step sequencer. I find it a bit too cumbersome to my taste and for some reason prefer the tone of the green units.
Pandoras are very useful practice tools.
The G5 is perect at what it does.