If I were in your shoes (and this is purely my opinion) I would pick BM1.
I had 3 BM and have not long added a 4th. The 4th BM I added sounds just like your BM 1 - I should mention that I have also changed a BM since then and swapped out one that sounds just like your BM 2 - are you confused yet???
Basically, my 'addition' I would have only known for just over 2 years come the wedding date but she has been such a good friend to me in that time. She is actually FH's best mate and we just click - I don't think it matters how long you have known someone, it's the type of friendship you have that matters!
My swapped out BM (just like your BM 2) wasn't really interested in the wedding, never asked about it and it just didn't feel right but I thought I would ask her as I have known her since I was 17 (now 33).
At the end of the day of course it is your choice but believe me, it's alot harder to get rid of a BM that is not interested and it's such a joy to have a bunch of them that are just as excited as you.
My money's on BM 1.......