I'm a professional brewer now, but at home I am a BIAB guy. This is strictly a matter of opinion (I predict the debate will be energetic), but I love that I never had to acquire any equipment at all to brew all grain. I can mash 23 pounds of grain in my 8 gallon pot, do a batch sparge in my 7.5 gallon kettle, combine the two, and make a kickass barleywine without doing the work to convert an MLT. Nevermind the money- I love spending my free cash on beer gear, but it's just a bonus that I never had to shell out for a craigslist gatorade cooler or stainless braid, nor invest the time to build my system. I get great efficiency with my hybrid-BIAB method and make award winning beers that I love to drink. Can't beat that in my opinion.
I totally have MAD respect for those who build their three-vessel systems though. That *redacted* is wicked! Some of yall have systems in your garages I would frickin' love to have at the brewery. All automated and junk. Crazy awesome!