which one's better n why? i was tryin to look it up and couldn't find n e thing

or does it not really matter?

I think that app has a slight adv in dmg due to overcharge? Not sure though

just preference...either instant repair or overcharge...
the Mana bomb is nicer for APP but both the skills kinda suck if you are going tower app anyway.

Pretty much. Though its nice with the versatility of instant upgrades.

Well if you put overcharge on you upgrade towers in about a second anyways plus you can heal and repair hell of allot faster with overcharge. So I would say App better.

apprentice is generally better since OC upgrade is only slightly slower than instant upgrade.

if you don't dps at all, it doesn't mater at all.

I'd say Adept because they scale much better with hero speed and hero casting rate.