Tower Health - 5 - First level only, Get more levels if the game is going to last long or the enemy is really pushing you
Tower Power - 1 - Towers already get splash to start. Doesn't grant enough damage fast enough to be worth it
Reinforement Attaack Up - 4- Only long games
Reinforcement Defense/HP Up - 3.75 - Not as important as the attack and only for long games.
Increased Gold Income - 5 - ASAP but only the first upgrade. Unless it's 5 on 5. Later upgrades just dont' pay off enough.
Increased Experience - 2 - Personally I never need it and it is only useful when you either have extra gold or the game is really close in level where 10% could tip the scales.
Decreased Death Penalty - 1 - Only decreases time dead. So noobs can die even more often. Needs to decrease gold or experience gained.
New Reinforcements - 5 - Good but it seems that some upgrades don't do as much as you would like. (angels)
New Weaponry - 1 - Fortresses just don't do the damage needed. Trebuchet's are anti building not anti personel yet we put them on a building so it can attack personel. Either the trebuchets need a buff or the fortress itself needs to be redone. Finger of god is almost completely useless due to it's low fire rate. More of an annoyance. Plus trebuchets are too late in the game to do much.
*edit* I like that someone finally did a post of this. This is what the devs needed.