As pilots, you don't have many choices when it comes to union representation. 1) ALPA, 2)IBT, 3) Independent, 4) No Union.
I have no idea how many pilots you have or what you fly. But as a general rule, if you have less than 100 pilots ALPA will not make any effort to organize you and usually is not interested. Especially if you fly small aircraft.
The IBT does have an "airline division", but as others have said here, it's not the greatest at representing pilots. Particularly if you are a very small group. (They do OK at Airborne and Horizon). They also represent some fractionals.
A small group can't afford to do much as an independent. It's not practical unless you have about 1000 guys or more and people among you with experience in labor relations. As far as I know, there are only 3 good independents. APA, SWAPA ,and IPA, representing American, South West and the UPS pilots. I believe AirTran also has an independent.
Of the 4 choices, ALPA is unquestionably the best. There are problems, but it is way ahead of the IBT. If you have a choice, IMO you should go ALPA. Even if you get nothing else at all from ALPA, you always get two things: 1) Good representation if you ever have a problem with the FAA; 2) The best assistance in the business if you have a medical problem. Just one (1) incident of either is more than worth your dues.
If ALPA isn't interested (from your post you are too close to elections anyway) you can still get ALPA unless they deliberately refuse. Your ballot should have a space for the IBT (Teamsters), for NO UNION, and for a write-in. So even if the IBT is the one trying to organize you, you can still write in ALPA if you choose.
A word of caution. If you do "write in" and one of the two unions does not get a majority vote, you could wind up with NO union, so be careful. In this case a "majority vote" doesn't mean 50% + 1. It means a majority of the votes cast; whichever of the 3 options gets the most votes.
So in an example if you have 100 pilots. 19 don't vote; 30 vote for ALPA; 20 vote for IBT and 31 vote no union..... what you get is no union. Be careful.
Good luck!