My thoughts:
Ratings:
-Melee builder 1,5/6
-Ranged 3,5/6
-Combined 4,5/6
-Magic 5,5/6
Melee-They rely on tech towers much more than other builders. They translate poor into mid, late game, You need good damage dealers later on with melee but they are expensive resource wise. You will need a lot of metal(reapers++) or a lot of mana+crystals(queens++) or a lot of metal and oil(battletanks++) to stay competitive. Maybe additional upgrade to marines(with decent dps, spamming a lot of marines is a bad idea late game wise) with high gold cost or with additional food cost would make help, or useful caster without additional resources required(or maybe if it was food). Also I don’t think they are that good tanks too. Maybe give them some thorns, damage dealt debuff like banshee? In my opinion, they should have one tower with like 2k+hp. Another problem- since your kill time is longer than for any other builder, enemy ranged sendings are even more deadly.
Ranged-Good damage, quite good mid, in late game(useful auras, debuffs) they may need some tanks though and after putting like 2 of each tower or so, their bonuses are wasted.
Combined -I think this builder is the closest one to the most balanced. You have good tankers(which can hold from early to late-upgraded, balanced upgrade cost), decent archers(losing on power in late though), and high elfs which I don’t like(mainly upped)(that fire shield is just soo bad in later waves, when your tanks die in few hits and mobs have too much health)- Generally any wave with multiple mobs can be more or less done without any use of aoe damage dealers, you cant say that about boss waves and aoe damage dealers-their effectiveness is heavily reduced.
Magic-I find them to have top damage, they translate to the late game the best- they all have very useful buffs/debuffs , they require only mana(and not much of it) and now, since banshees can stun enemies for quite a long time, they can even live good without tanks. I think, you should consider reducing their stun duration and maybe make more adjustments here and there.
Other thoughts:
AoE:
I will repeat that once more:
Generally any wave with multiple mobs can be more or less done without any use of aoe damage dealers, you cant say that about boss waves and aoe damage dealers-their effectiveness is heavily reduced.
If you could give every mob with aoe some useful effects(like slith does) they wouldn’t be so bad. High Templar(upped) and High elf upped, collosses- I wish they had some extra (useful) effects like magic builder towers do.
Sendings:
Any chance we can see more sendings soon? Maybe food-iron combined or even ones with cost of 3 resources?
Also I would like to say, your map is pretty fun to play(maybe some day someone will make from this A+ game, just like what happened to DOTA :) ).