All antipsychotics CAN make you gain
weight, but some are worse than others.
Geodon is supposed to be
weight neutral, and Abilify mostly weight neutral (won't make you gain or lose). Saphris has gotten a lot of good reviews in the weight department, and I believe Latuda has as well, but these are both still brand only, which might affect insurance coverage (and will affect cost).
Unfortunately, there's no way to know for sure if a med will cause you problems without trying it first.