Listen to the Rolands and the Korgs thoroughly before you buy, both through good headphones and amps/monitors. Also, play them both a lot; you may find that you definitely prefer one keyboard's action to another.

If you can, buy from a store that offers a generous, no-hassle return policy. It is hard to tell if you'll like a synth from what you can experience in the store. I've owned both of the synths you mentioned; I still own one and have returned the other...for purely subjective reasons.

Good luck!