Canuck,
You'll be fine in all those types mentioned at Standard, though each has it's pros and cons. The Slingsby, though I've never flown it, is known to have a pedestrian roll rate due to the long wing and dihedral but, if flown properly, should be fine at Standard level. Citabrias and Decathalons are also perfectly adequate. Don't waste your time in Cessnas, though, as they just aren't really designed for that level of work.
Personally, I think the Bulldog is a lot of airoplane for what it is, being heavy and full of switches and stuff. You find the Pitts to be very common in Standard because it's perfectly suited to it and is easy to take to higher levels of competition, whereas the other types you mentioned probably wouldn't realy get very far in Intermediate, and you can forget Advanced.
Hope that helps.
PPL152,
I don't know what the regs or competition opportunities are like in Malta, but the British Aerobatic Association runs along internationally standard lines so much of what's on there would still apply if that's what you're looking to do.
Cheers,
Pitts2112