Before choosing the software to power your forum, take advantage of free trials and demos beforehand.
You might blindly choose a software that you end up hating to use. Then, you have to go through the trouble of merging software. Sometimes, you have to use another software just to be able to merge one to another. It can become a nightmare.
Test it out first and go with what you love best.
What do you all think about this sort of thing?