I have done all 3 styles (extract, biab, non-bag all grain). Personally I'm not the BIGGEST fan of biab, but that's just me. It has nothing to do with taste, just something about the bag in general... it made me feel like I was making a gigantic cup of tea with a giant teabag. There is absolutely nothing wrong with biab, it just wasn't for me.
I first started with 1 gallon all grains. Tried a 1 gallon extract and found it boring, went back to all grain. Moved up to 5 gallons, but did not want to spend the money for the large, all grain equipment right away, so I did 5 gallon extract brews with partial boils. Got the hang of brewing by doing various 5 gallon extracts and 1 gallon all grains. Finally bit the bullet, moved up to 5 gallon (and one time, a 10 gallon) all grain and have never looked back. I love it. Any sort of all grain feels more like a legit form of brewing, more like how the commercial brewers do it. Extract makes me feel like I'm playing with a little kids chemistry set... just add add pre measured substance, provided fully for you, at certain times.... and get a beer at the end. It works, but I like it less. Biab is a great way to jump into all grain brewing. It makes smaller batches (3 gallons) so you aren't overwhelmed by 5+ gallons right away. Like I said, it was not my favorite style, but it did teach me plenty and jump started my interest in all grain. I say give it a shot, many people love it and stick with it, some use it as a spring board to bigger things. What's the harm in trying?