Re: Why did you opt for phpbb?
				
				
                
                
                    
						
                
                
                    
                        I spent more time than I'd like to admit evaluating many different types of forum solutions and I narrowed it down to 
phpbb and 
vbulletin. Vbulletin costs $180 but is probably the best solution out there for the money. The reason I decided against it was because it was too powerful and feature-rich for what I needed. Those are not bad features...I just didn't want to spend days trying to configure every little option. You also have to buy an aftermarket 
SEO plugin which costs close to $200 if you want clean urls and page titles. Phpbb was my 2nd choice and was easy to modify (all for free I might add) so I went with it and have been very happy. The only thing I don't like is the lack of plugins (mods) and doc on how to install them. It also didn't come with an rss feed nor was it 
SEO'ed correctly so I installed two mods. 
I really wanted to use BBPress but in my opinion, it's just not mature enough yet. I liked the integration with 
WP but the feature set just wasn't strong enough. I bet in a year or two BBPress will be more of a contender but it's just not there yet.
I used 
Simplepress about a year ago and thought it was a great plugin. The only downfall at the time (and maybe it's been corrected) is the slow speed. It's nice because it fits right into your existing WordPress site though.
I recommend checking out 
Forum Matrix which will let you compare dozens of different forum solutions side-by-side.
Good luck with your selection!