A droideka? Worth three commandos? A single good commando could take out three droidekas simultaneously. A well-placed EM Grenade or two batters their shields aside, and a few good shots finish up the rest. Or, a good Pulse weapon, like a special rifle, or ion weapons, would bleed the shiled out and scramble evry system in the droideka's hardware. A commando in ROTS on Utapau takes out a Crab Droid in what has got to be the coolest trooper maneuver in the movies.
Hmm by all logic the X-wing wins, because its the newer fighter you don't make weaker fighters then you had years ago you make them stronger more powerful faster, unless of course the price was to high and they had to downgrade to be able to get ships but I have no reason to believe that, so X-wing wins.