[quote="Shawn"]
I like many.

My favorite is XenForo. It's the most updated platform.

I started using phpBB1 and then soon went to phpBB2. This was late 90s/early 2000s era.

I used Simple Machines Forum, MyBB, vBulletin, and Invision Power Board, too.

Nowadays, I have multiple XenForo powered forums, a vBulletin 6 powered forum, a MyBB, a phpBB3, and a SMF. The last three are mainly because I wanted to see what the top free platforms had to offer these days since I hadn't used them in years.

Out of all of them, phpBB3 is nice but the default spam-controls suck. MyBB could be the best but it's not even responsive out of the box. SMF is great and responsive but it looks like the first software ever made because the look isn't modern looking.
[/quote]

When it comes to top free i am confident you got to put proboards on that list.