@Sublime one of our resident experts along with
@zkx14 ...
Auto or wheel gun?
Personal preference on caliber.. for me, reliable brand, slim design, light in weight and not super expensive so if it ends up in an evidence locker you aren't out a big chunk of change.
Springfield, Smith & Wesson, Glock and Ruger come to mind
9mm is a fairly light round and not overly expensive to train with