@scoobert, I find it cool that you want to dive "deepish" wrecks. I understand you a lot! If you are willing to travel a bit, you may see unbelievable things, the kind of stuff that inspires Hollywood movies (not joking at all!).
Now, this is going to be a bit long; sorry for that
Although I like that you are so fascinated, I can see two things that are potentially not good in your question:
- the "quickest" path;
- deep(ish) air - I add "ish" because deep stuff is another realm, and I bet you will be fascinated once you discover it
Now, deep decompression dives add a series of risks to your hobby; now, I can think about only two ways to tackle these additional risks:
(1) being reckless and going for the quickest path possible;
(2) being responsible and taking the appropriate training step by step.
I am not going to discuss the first option, being reckless, for a series of reasons; one of the most important ones is that I think you are a responsible person. Otherwise, you wouldn't be asking.
Speaking about taking the appropriate training, we can define the following steps:
{A} excellent basic skills;
{B} experience;
{C} deco training.
Regarding {A}, I am primarily referring to the following:
- buoyancy and trim;
- sharing gas;
- using an SMB;
- be self-reliant;
- be aware of your buddies if you want to dive in a team, or be able to understand when you need extra redundancy if you wish to dive solo (I am personally against solo diving, but it's a very personal choice - anyway, if you want to go for this path, you need to understand the risks);
- proficiency with your equipment;
You can see that already at this step, which is the very first one, you need to define a series of things:
1. Do you prefer solo- or team-diving?
2. Do you want to dive back-mount or side-mount?
3. Which will the typical conditions of your dives be? (concerning visibility, water temperature, current, and access to the water)
I am a strong proponent of taking intro-to-tech style courses as soon as possible since all the (good) instructors I met suggest it. If you do it, you will immediately learn the "good habits". If you don't, and your OW training isn't top-notch, the risk is that you will develop bad habits. When you, later on, take tech classes, before learning the right skills, you will first need to "erase/forget" the bad habits: this process can be VERY painful and prolonged, trust me
Regarding {B}, the point here is to dive until the basic skills are automatic for you. In other words, you don't have to think about being in an appropriate trim, about your buoyancy, or how to launch the SMB. I strongly discourage you from taking any advanced deco training before at least 100 dives. Here, with advanced, I mean the use of a stage with nitrox up to 100% oxygen and mandatory deco up to 30minutes; you may evaluate dives that are significantly less complicated than this with less experience, given that your basic skills are excellent.
Lastly, regarding {C}, you need to choose the training that you want to do, find a good instructor and take the course, and then you are ready
Now, a couple of details regarding the instructors and the agency.
Point 1. No matter the agency, you need to evaluate the instructor.
Even if some agencies have better control over quality than others and thus can guarantee that the diving skills of the instructor are high-end, you still need to be sure that your personalities fit pretty well together.
Point 2. Standards vs free.
There are two ways of diving: standardized team diving, and non-standardized diving. Standardized team diving means you have slightly less choice about the equipment you can use, gas, etc. On the contrary, with non-standardized diving you are free to do whatever you want (although very deep air diving starts being discouraged almost everywhere).
You may think: what are the advantages of standardized team-diving? Easy: when you dive with other people, you know EXACTLY how they will behave underwater, what is their plan, what is their equipment (so you will be able to help them quickly, and vice-versa), and so on. I do this kind of dive, and I can tell you that I may do very cool dives with people I have never met before.
Point 3. Agency matters up to a certain point.
As I mentioned, some agencies have excellent quality control and ensure that their instructors have excellent skills and decent diving experience beyond instructions. The most well-known is GUE (there are some others). Remember that GUE teaches a standardized approach to diving: no side-mount (except if you are a very expert cave diver), no rebreather before normoxic trimix, and no deep air. One of the main advantages is that you only need to ensure that the instructor's personality fits your one since the diving skills are almost certainly there.
Some agencies are very spread and well known. PADI is the most common one, but its business model is oriented to vacation divers and does not emphasize high quality as much as other agencies. However, there are some damn good instructors with PADI - the only problem for you is: "how do I recognize them?"
Lastly, TDI and IANTD are among the most common agencies for tech diving. The same considerations for PADI are valid, although their customers are fewer vacation divers and more (only) tech divers. Overall, I think their quality control is not as high as in GUE, but as for PADI, you may find excellent instructors here.
Many other agencies fit more or less in the previous categories, and, as you have already understood, there are great instructors in any of them.
--- How would I proceed? ---
Take GUE fundamentals, hands down. You can rent the equipment (I bet with a discounted price, so you will not have to sell your liver), discover the standardized team approach they have, and learn excellent basic skills. Then, if you don't like this approach, you can always go back to other agencies; in this case, I suggest you take a rescue course, dive a bit, and look for a good instructor for an ANDP course. If, on the contrary, you like GUE, you will just have to follow your instructor's suggestions.
A final remark: because GUE has such robust control of quality, the recognition of certification from other agencies is slightly more complicated: you need to do an evaluation dive with an instructor evaluator (IE). And because GUE is a relatively small agency, it is hard to find IEs ready to do it with you in a short time. Namely, the best path for GUE is to take the fundamentals and then continue with GUE. On the contrary, if you take fundamentals with GUE and get a certification, your skills will most likely be accepted by other agencies (it may sound "arrogant", but in fact, it has to do with the standards of GUE that other agencies usually ignore). Another good reason to take GUE fundies