Actually I recommend the one ship you didn't list... The HWK-290. It is a decent support ship. You can use Jan Ors to add an extra attack die to one of your other ship's attacks or use Kyle Katarn to crap out focus tokens everywhere. Then again the B-wing can make for another good one. Lots of players use the B-wing. The Y-wing does not see too much action these days, but when it does it is usually as a support ship with the ion cannon turret.

Though with rebel aces comming out next month most likely I would say hold off and just get that. Then you get both an A-wing and a B-wing and both with some of the sweetest upgrades either ship has ever seen.

Tie Advanced! (Just kidding). Buying one Z isn't going to be especially helpful; I'd only go that route if you're buying 3 or more. I'd look at the E-Wing, as it's a 3 agility ship with really good named pilots that have interesting abilities.