I like to use the Chapman stance, which you
never hear about it seems. The difference between the Chapman and the Weaver is the Chapman uses a straight strong arm. I will go from Chapman to Weaver as the situation dictates.
The Isoceles is very much in vogue right now, and for good reason. For the shooter wearing body armor (such as a policeman) the Isoceles has the less exposure of unprotected COM.
It's actually good to be fluent in all three, as well as shooting with either hand from cover. Because you cannot predict the nature of your cover, you cannot predict which technique you will need.
edited to add
this link