I think I would bring an old Korg Triton or X5. I think the latter is a metal standard.
I use an MX49, but I"ve remembered trying an old Triton in a music store back when I was a kid and it sounded good.
Some good keyboards for general rock would be any old ROMpler at least even a Korg X5D or Korg M1, which is what all the black metal bands used to use.
Anything that has good organ, strings, brass, piano, Rhodes or Wurlitzer, and a few classic synth sounds like the Jump, Final Countdown, or other similar synth brass or 80"s sounds,