Depends on so many things, most of them being personal.
One criteria I value a lot is the possibility to wash your undies easily....
Another obvious one is how the standard size would fit

And again one more is not being too much buoyant
See if you want 1 piece, or separate pants and top. (I prefer 2 pieces so I can change easily the top to a t-shirt between dives)
Do you have a p-valve (then indeed, a zipper is convenient - I dont have one :-(
An inside pocket can be useful - I dont have one either, and it cost me to lock my keys in the car once -
So like everything, plenty of possibility without final/ideal answer.
4th elts arctic and mk2 seems popular around socal, but there are plenty of options, and many also seems to use ski-undies too.
good luck