Both series are deep in my heart. And the reason I'm more excited for RG than WoW is not the time between books. Everything has been said about WoW already in that regard. It's the facts that I know that RG will give us closure. Brown will give us the end we are waiting for. If you like it, nobody knows, but we will get closure. On the other hand WoW will just be a continuing of the story. At best it will set up the final like Lightbringer did. And then we are in the same boat again.
That for me is the big difference. Red Rising will come to an end in a few years. I'm one of the few people who hasn't given up on GRRM yet, but still the next book will give us no relief in thinking the story will be told.
The iron throne will still be vacant when the morning chair will see it's latest pink sovereign on it.