Hmm turnbased or real-time that is really the question... I prefer turn based games, but lot combat in these games starts to get very boring when you have a lot of enemies, fighting single encounter 10+ enemies can get at some point a big deal. Real Time Combat is fun, but it can be affected badly by small mistakes in pathfinding, scripts of some abilities. My favourite Turn Based Combat in RPG is Temple of Elemental Evil, my favourite Real Time Combat in RPG is in Baldur's Gate 2. And there is a mix of these two seen in many JRPGs. What I would recommend you is to sit with your guys and ask yourselves what game you played had combat system you liked most And then try to make it in your game even better
Whatever will be your final decision, I wish you luck and as much sales as possible, and please, when you release the game, put it at some point at GoG as well. We, no DRM folks, will be very grateful, and we can really appreciate the love you show to us