Exactly the same effects that're on my board now. CC, FRV-1.
I was in an 80's and 90's cover band for 2+ years, did most of the keyboard parts (I was only instrument besides drums/bass). I could have done it all with guitar straight to amp, but the delay really helps with songs like "Pride" or ambient keyboard swells.
You don't need much. I found that having less meant my audience got more.