welcome to thr.
i had a serpa and used it alot, it didn't conceal well so i had no need for it. the button on it is a neat idea, but retention is a training issue imho not something that your holster should do for you. i am not a fan of retention devices on a ccw holster. ask me why.
have you ever done the Tueller drill? it is hard enough with a slick opn top holster, even harder form under concealment, made even worse when you have to worry about things like buttons and gadgets. heck it is even hard when the gun is alreayd out of the holster in the covert ready.
good holsters? it depends what you like, do you like kydex? leather? do you want iwb, owb?
if you want leather, i suggest you check out Don hume, they make great stuff. If you want kydex you can't go wrong with blade tech they make great stuff, iwb, and owb as well.
check out raven concealment, and comp tac mtac they are sweet holsters as well. there are many options out there, and many more than i have given you, however those are the ones that i recommend and they are the ones that i have put to the test and other people that run guns for a living, recommend as well.