I have always used Yamaha MSP-5 (early version) monitors for everything, and I won't
replace them until my room sounds better. For home keyboards (including piano, Rhodes,
synthesis, bass keyboards, etc) they do their job.
That said, if you want to
buy something new, there may be better price/performance ratios now (when I got the MSP-5
they were the cheapest available monitors!)
Best
-j