At this point in my life, I can get a pretty good idea by doing a little research and one in-person handling. I've made a few questionable choices (mostly related to a "can't beat it" deal, but no really bad ones.
Once I have it in my hands, one range session gives me a good first impression...and you know how those are. Very, very few times has a first impression been reversed...actually, I am trying hard to think of one example, and so far coming up blank.
Once you know what you like and what works, you will find it pretty easy to filter any future purchases...and I don't mean that you have to stick with your traditional choices.
What do you do if it's the issued departmental carry weapon and you decide that it's not "suited" for you?
Do you quit your job?
Well, since my employer does not pay me to carry, or pay for my carry choice...that is a moot point.