Like Rolf I'm under the Fintrack agreement with Choice so the flat fee structure works very nicely. I wouldn't really care otherwise, I was with PLAN for a while and I don't see a whole lot of difference in the service, although my gut feeling is that PLANs agreement is probably a bit more friendly to brokers wanting to leave.
Choice are starting to put a lot of focus into helping their brokers build better businesses. Like most aggregators they have lots for new brokers and a good service to the larger groups, but they are trying to address the brokers in between. It's not there yet, but they are improving.
I wouldn't even consider a franchise. Brand recognition can be nice, but it's not what really counts to the customer at the end of the day. I'll take a few high quality inquiries over lots of low quality any day.
Software isn't worth worrying about. I've yet to see an aggregator with (free) software that meets my business needs better than the package that I pay for.