AaronR103:
Hey all. I'm looking at putting a together a set of steel doubles and was wondering what size tank most people get. I'm looking to be versitile here for tech, cave, and recreational dives. I'm looking mainly at the LP 95s or 105ish (i've seen 104, 105 and 108 in this range).
There's not really any universal "best" tank that will cover you for all types of diving. Most people tend to specialize, and choose the tanks that best support their particular interests.
For cave diving, the clear choice is the "old school" Pressed Steel LP-104s (now sold as E8-130s). These are just about the perfect combination of size, capacity, and buoyancy for cave diving.
They are a little unwieldy for boat diving however, so most folks prefer smaller tanks for that. This works well because the bottom times are typically not as long on open ocean dives as they are in caves.
For ocean diving, the choice seems to be either AL80s or lightweight LP-95s, such as those marketed by Faber and OMS. The final choice is dictated by how much gas you need for the dive, whether you are diving wet or dry, etc. I think LP-85s and LP-108s might be a good choice for this as well, assuming you are diving dry.
So the answer to your question lies in what type of dives you see yourself doing in the immediate future. Most people purchase their first doubles for ocean rec/tech (i.e. deeper dives that are mostly still within the NDL), which makes the AL80 an obvious good first choice. when you get a drysuit and purchase larger steel doubles, then the AL80s can broken down and made into stages, so there is no need to repurchase or discard anything.
Without any more info than what you've given on your interests, then I'm inclined to recommend AL80s. If you can give us more specifics, then we might be able to offer other (or different) options.