I watched the video that DRiS has posted for how to measure for a USIA suit. I would have no qualms about taking the measurements per that video and ordering the suit from DRiS.
Both my suits are diagonal front zip. I have no trouble totally dressing myself - then making fun of my dive buddies with a back zip that need my help getting in and out of their suit.
I have experienced exactly zero downside to having a diagonal front zip. I have also really enjoyed my ability to take a whiz during a SI without having to even take the top part of my suit off.
I have been using the Kubi dry glove system, which fits on to the stock latex wrist seals. I really like that the rings come in different sizes, so you can get the lowest profile possible that will still fit over your hand. I have the 80mm rings and they are noticeably lower profile than other round ring systems that I've seen. And in over a year with them, my hands have only gotten wet once - the last time I dived, when I finally got a pinhole in the original set of rubber gloves that came with the rings. I found the identical gloves online to order replacements - for $2 per pair. I also like that I still have wrist seals in place, whether I am using my dry gloves or not. And I like that the whole system is a few machined aluminum rings, some O-rings, and inexpensive rubber gloves. Nothing that would be expensive to break and have to replace. My tech instructor has been using the Si Tech oval rings that came on his Waterproof D1 suit over the whole time I've had my Kubi setup and he gets out after almost every dive complaining about flooded gloves. He finally just ditched those in favor of some new system, but I'm not sure what it is (other than I know it's not Kubi).
For dry gloves, specific things I personally would definitely avoid are:
- Gloves that have to be attached to the sleeve before you don the top of the suit.
- Gloves that don't let you also have a wrist seal in place at the same time.
- Gloves that are expensive to replace if the glove gets a hole in it.
- Any system with plastic parts that could possibly break (like plastic tabs that could possibly break off).
As soon as I settle on a dry suit that is a "keeper", I am going to get the Kubi fitted rings installed, so I'll have silicone wrist seals that are replaceable. And I'm going to get the Si Tech Quick Neck system installed, so I have a silicone neck seal that is also replaceable.
Lastly, if you have the option, DEFINITELY get thigh pockets on whatever suit you get.