I know the GP is going to overwhelmingly vote FH. I'm 50% there myself. But I will say, the other day I played a RCT for the first time in a long time and really enjoyed it. Maybe perhaps it was because it was next to Monopoly, which I think of as a lesser version of the same layout, and perhaps because I understand the RCT lingo as I played the PC game, but I think it's an underrated game based on the bad rap it usually gets.
Don't get me wrong, I still like Funhouse, and when we had a 100+ pin arcade over the past few years, it was probably one of my top games, but I don't think it has a ton of replay-ability. But then again, looking at your collection and the time frame you plan on keeping this game, FH may be a perfect fit.
Either way you can't go wrong between RCT and FH, and at those prices, you shouldn't have a hard time moving either out when CGC finally starts shipping MBr.