I've been diving 2 years now so here's my advise for what it's worth:
DUI Drysuits are top of the line but expensive. I just bought a Bare HD Tech from divetank.com for about half the price with hood, fleece, trek boots etc. Do some research here as it's a big $ purchase and you want it to fit right.
BC: If you're even thinking tech. etc. go with a BP/W now! I went from AOW to G. Cayman with a FredT 9# backplate and never looked back. Totally streamlined, no inherent buoyancy, a dream to dive. Lots of homework here to figure out your trim and weighting. I now dive the SS plate with Aluminum tanks and shorty or drysuit and have an Aluminum one when I dive my steel tank and shorty in North Carolina. I can go to doubles anytime now, just have to buy a doubles wing. Will last forever.
Regs: I have the Apeks ATX200. Absolute awesome breather at depth. I wish I was a tech diver just to see how it breathes at 300 fsw
Also easy to get parts for and easy to rebuild. Something to think about if going tech. I'd pick Apeks over Mares.
Get the Apeks octo unless you go with something else. Stay away from the airsource.
Fins: Try splits and Jet fins. I LOVE my old Scubapro jets with spring straps (gotta have 'em) I tried splits in a pool. They do seem to "become" more efficient at speed with a modified flutter kick but the Jets are POWERFULL off the "line". In a strong current I'll take the old jets. I think for me the jets provide the best overall performance for all of the types diving I do (wrecks, tropical-reefs, quarries, shore dives, cold/warm etc.).
Computer: I have a Suunto Vyper, I love it. Easy to read, everything is there. Everyone says it's conservative but I've yet to have it tell me to head up before anyone else. I can dive Nitrox with it or use it as a bottom timer (important if you go DIR or deco diving). You may want the Vytec (with or without transmitter) as I believe it allows gas switching etc. during the dive. Again, something to think about if going on to tech.
Mask: I just started diving a Mythos. Awesome mask! I had a DeepSee basic mask, no comparison! Incredible field of view. I used to have to bend down my head to see my SPG on my left D-Ring. Now I just look down through the mask.
Hope this helps, have fun!