The trouble is that none of these questions can be answered by anyone except the diver for whom the BCD is intended.
I assume that your diving is 100% recreational as opposed to rec-tec.
From there, the decision you're going to need to make is: traditional jacket style, or jacket style with back inflation (such as the Ariel), or back plate and wings (the OMS that has been suggested.
Fit and comfort is totally personal to your body shape and to some extent, your emotional comfort with the style of BCD. Are you busty or flat chested? If the latter, pretty much everything will feel comfy!! LOL Typically, if you're well endowed in the chest area, you'll find harness/BP/wings set up or the ladies BCD's more comfortable. With the harness set up, the shoulder straps sit around your armpit area, so there's no interference with your trophy up front. Likewise, ladies BCD's such as the Ariel allow you to move the shoulder straps to adjust for the bulk up front. If you're petite, a BCD such as the Zeagle Zena can be more comfortable and stable on you because the corset holds the BCD nicely in place, eliminating that feeling of your BCD being on a dive by itself, with you somewhere close by. The one thing that is very nice to have and most ladies BCDs come with it is a sternum strap: it holds your shoulder straps together across your chest, preventing the straps from falling off your shoulders and re-distributes the weight of the gear so that it's not all two concentrated spots on your shoulders.
The other factors are how much buoyancy you will need, which depends on how much lead you'll be carrying, which depends on a number of things, one of which is the type of exposure suit you'll be wearing.
You mentioned a dry suit, which brings up the issue of the inflation valve. Mine is on the chest, which I find to be an interference with my jacket style BCD, which is why I dive an OMS set up with my dry suit.
The point is: what's comfortable for one person may not be comfortable for you.
Good luck and have fun. And remember, although you'd like to buy just one BCD for your entire diving career, you have no idea at this point in time how far you'll go or how your interests will evolve. My first BCD was a Sherwood Luna. At the time, my only frame of reference was rental BCD's which were too big for me. Well, I thought I'd died and gone to diving heaven when I put that Luna on. Then I started diving dry suit, and it became very obvious that the Luna was too small and bulky with a dry suit. I now dive an OMS set up with my dry suit and absolutely love it, but who knows if that will continue to fit my diving needs and style in the future? I still love my Luna, but I use it only for pool dives and tropical dives.
Good luck, and don't forget: gear shopping is as much fun as diving!
