4 x 3L
AL40
2 x AL80
2 x HP100
That is the primary collection that gets use
I keep an old 72 in the non-dive boat, just in case of anchor retrival or de-fouling needs. The smaller diameter fits under the seat where the larger AL80s and the like just don't fit. It was also my first tank and the last of my original dive gear that is still usable.
There are a few others I don't really have inventoried. There is one that is condemned, but useful when you want a tank shaped object you don't have to care about. Some 1800 PSI bastard. Just picked up a little AL13 that is out of hydro and VIS but still full of Argon.
Then if we start adding in the welding cylinders (CO2, MIG mix, Oxy, Acetylene, Argon, spares)
There are probably more that I am not thinking of right now.
All personal use, no training. Couple that I should probably get rid of.