... on what kind of diving you will be doing (as usual).
I'm a standard "off the peg" wetsuit size, and I usually dive on holidays, so far only in the warm blue waters of the northern Red Sea.
Since completing my OW+AOW certification courses, I bought a mask, snorkel and a shiny Suunto Stinger dive computer
For the kind of diving I do, Tables are impractical, as ALL dives are multilevel. I've just returned from a liveaboard in the Red Sea, and I would have been breaking the PADI tables on the first of my 22 dives that week!! On the other hand, I feel better having my own computer, instead of just trusting the divemaster's, who wasn't always at the same depth, for the same duration, etc.
I think my next buy will be a BCD, since the bad fit of the rental ones and the consequent ill u/w posture are really starting to annoy me.
If you have trouble renting a good [fitting] wetsuit, you don't trust the renters to maintain the equipment properly, etc, then of course your priorities would be different.
Just my EUR 0.02 ;-)
Dive safely