I will pick vBulletin as it's the only oone I have used and it's very good. I love themes as it's way more good looking compared to the others forums. Anyways I can't talk about editing and that as I didn't did a lot of that ;)

In order:

1. Invision Power Board
2. MyBB
3. vBulletin
4. phpBB

I believe IP.Board is on top because it's extremely clean and organized, as well as user and administrator friendly. It has always been my favorite, and it still is, though MyBB, second on my list, is starting to take over the number one position in my mind. Why? MyBB is, just like IP.Board, clean, well organized and user and administrator friendly... However, it has an additional benefit, which is the fact that it's extremely easy to customize and add on to, whether you're an experienced forum owner or not. Onto vBulletin. The back end is terribly messy and unfriendly to anyone that hasn't used it before, or has extensive experience in managing forums. Thinking about it though, if you're willing to drop $200 something on a vBulletin license, you better be damn good at managing forums. With only minor edits, vBulletin's front end can become just as, if not messier than its back end. Overall, I greatly dislike vBulletin for those few reasons. And phpBB... Whatever.

Three months ago, I would've said phpBB. Now, I say MyBB.

In order:

1. MyBB
2. IPB
3. phpBB
4. vBulletin

To be honest, I'd rather have no forum than run one of vBulletin, especially the 4.0 series.

I think i would have to choose Mybb

It depends on what you are going to use your forum to.
If you are going to sell a product on your forum then i would clearly choose vBulletin.

MyBB. It's easy to use, and it's very Powerful and Secure

I like Mybb as it is free and has many plugins and themes.

like MyBB so much, it's powerful and so easy! With a lot of plugins developers!

The first forum sites I was on were Invision,
Since then ive grown to be fond of MyBB