speed and agility are, of course, the bread and butter for any receiver because you'll need to be creating separation from defenders to make plays.
with that said, i would monitor your TE's progress every season and adjust accordingly. there isn't really a cookie cutter build, and remember, opponents, your depth chart, team philosophy and play calling are all partially responsible for your player's success. (i.e. if your O coord rarely looks deep to your TE speed is going to be marginally important)