Ultimate Member is not free. To an extent it is but limited. It is paid for what you want that buddypress has. That isn't saying much though. For what is free on Ultimate Member is nothing compared to buddypress unless you pay for the extensions and that means it isn't free really at all.

If you want just a few features with Ultimate Member then use it but to use with bbPress you need extension and pay. If you want certain other features its paid. As much as they charge for the extensions, it is expensive for a site.

Just too bad that buddypress developers want to keep theirs basic styling. If I was made out of money which I am not. I would get this plugin on my website and buy the extensions. To say it is free is kind of over doing it.