TECHNICAL DIVING FOR A LIVING is very hard on kit. Whether its just cleverly marketed but not so cleverly constructed, or simply incompatible with RIBs or baggage-handlers, the outcome is often the same - breakages and floods.
I fell for my early instructors blarney and bought the noddy-kit they recommended simply because the dive shop had no other brands.
Ive had more kit break at critical moments than I care to remember, but after 15 years of kit-related near-misses on deep dives, I finally feel fairly happy with all my equipment. There is no item among the following that I wouldnt take to 200m or deeper.

Ive tried all the big-boy manufacturers wet-n-dry suits and Chinese export patchwork specials. One new suit even filled up on its first outing as I walked down a slipway - CE marking is a beautiful thang!
If I resemble a wet T-shirt entrant after a dip, the suit gets binned.
In 2002 I was driving to Coniston to do a 237m mine dive in awful conditions, and stopped off in Bradford to get measured up by Otter.
Two days later, I had my made-in-the-UK Otter Skin membrane suit. It actually fitted someone similar to my size, and did exactly what it said on the tin. The deal-clincher was the loan from Otter of a heated undersuit.
The drysuit was a Britannic with a few custom mods. It did its magic and I still have it, along with a couple of newer versions.
I prefer back-zipped suits, because the cloth can be cut closer. Many front-loaders have a bingo-wing look that is neither flattering nor useful.

Ive never been built like a racing snake, so I dont feel the cold as badly as some. Even in UK winter-quarry temperatures, I feel toasty in a 200g undersuit.
If its a special occasion, I have been known to don a 300g, but even in freezing water its been uncomfortably warm.
If I was doing anything prolonged in water colder than 6c, I would opt for a neoprene suit at least 6mm thick.

Ive lost count of the times my lights have gone out in deep water. Generally it is the big expensive primary light that popped at 120m, despite the maker claiming it was good for 200m. Generally Ive found that American lighting is most likely to have overstated depth capability. I love seeing the old watertight to 2000ft chestnut, only to have six of the little luvvies gurgling in unison at 150m.
After wasting thousands on ever-better HID, LED or halogen uber-torches from around the world, by chance I started using various Green Force models. Made in Belgium by a company that makes aircraft parts, they do what theyre supposed to do.
My favourite is an HID 50W Pro head with the smallest battery-pack (F1, I think). Its fantastic, incredibly bright, small and, most important, reliable in deep water.
If Im travelling by plane I always take it, but for home waters I have giant dual 150W HID heads
with batteries as big as fire extinguishers. If the visibility is not good enough for me to get maximum advantage from them, I can play semaphore with the police helicopter that always seems to hover over my house in London!

Apparently I have a reputation for disliking rebreathers. Far from it, CCR is a great tool - at least, it is in the hands of users who have more dives than forum postings.
Coroner reports show that Joe Bloggs often doesnt know whether his unit is upside-down or not. The sort of fundamental questions asked on
the ever-more censored rebreather forums make you wonder if the thread posters did a rebreather course at all.
Ive had a go on many CCRs. Ive never used a dive computer that didnt have the occasional senior moment, so electronic CCR is not for me. I have a Pelagian rebreather thats manually controlled and, with its diminutive size, perfect for travelling.
Ive only used it to a little over 180m to date but, touch wood, its been perfect.

I use a wing from OMS, a dual-bladder version with 60lb of lift. Its red for increased visibility and has bungees to aid stability. If that makes me a stroke then youre a sheep - baa!

Now we are talking religion. Ive tried everything, and even free regs from sponsors have been potentially life-threatening in deep water.
I think any regulator will work to 150m, with enough helium. If you arent planning to go any deeper, keep your old Snark or Merlin twin-hose, as there is little better on todays market.
For crazy dives below this depth, then, Ive settled for Mares Abyss regulators. My Mares regs remain reassuringly constant whatever the depth, and cold water doesnt bother them at all.
The second stages are metal, so even the most chimp-fisted baggage-handler would have to get a run-up to knacker them.

For technical diving there isnt much from which to choose. I have had a VR3 for five years and am pretty happy with it. I also use a Nitek He, because I like the no-deep-stop-nonsense deco profiles it gives.
It also has a nice temperament, so I dont have to keep getting it fixed every six months.
More recently, I bought an OSTC dive computer from Germany. It lets the user program the algorithm and I have in it a copy of my Decochek software, which nine out of 10 skeletons given the choice would prefer.
The OSTC does trimix and open- and closed-circuit and has a brilliant OLED screen, all for 400!

Fins seem to be another emotive subject. I started out with old 12in 78 LPs to move me along and these were fine, even in a maelstrom. By 1995 I had tried every permutation of flipper and they were all either too stiff or merely all right.
My local dive shop introduced me to Force Fins, and Ive never looked back. They last forever, look cool, you can walk in them, climb boat ladders and they are virtually cramp-proof.
For those with fat wallets, the company does a Millennium Falcon version with turbo whiskers etc, but my standard Pro Force pair has done me proud for more than 3000 dives.
Akin to Marmite in that they take an open mind and some getting used to, once you get the knack they are the ultimate flippers.

A mask has to be comfortable and not let in too much water. I have several Mares Liquid Skin masks, all the single-lens type, as they feel more comfy.
Before these I had a penchant for Tusa Hyperdry masks, with the big single glass with purge valve under the nose. They look like small televisions. I still have a couple, but people take the pee when I wear them for some reason - jealousy, most likely.
I once overheard an instructor telling his flock that they should use two-lens masks because if one glass breaks you still have the other one to look through. Handy hint.