SureAI

So I plan on making this magic melee warrior type who uses sword, magic and summons to defeat enemies so what armor type would be the best to spend my points on? I don't know yet what armor type has the best available stats which would supplement this playstyle. I don't want to waste for example all on heavy armor only to later find out there's this badass light armor set.

Robes (that boost magic) are light armors, I'd invest on that.
Best robe so far I've found has armor ~100, about same as my normal light armor (I'm not using magic at all, just melee)

Would love to know where you found a robe with 100 armor rating.

I use light armor so I don't pay that much attention to heavy armor, but seems to me I can find light armor that is better than heavy armor. What you find is generally better than what you can make as armor you craft can only have 1 (weak) enchantment, and what you find often has 4 enchantments, plus wearing more than 1 of the same set gives even more bonuses. The armor rating also seems to scale -- I have a L78 character with crafted exquisite aeterna cuirass armor=106, and another character L65 has the same thing but armor=73. The best heavy armor I could craft is the Cuirass of the Righteous path (exquisite) by character L78, Handicraft 100, and armor = 73!

Re robes, my L65 character has Robe of Tribunal armor=55; my L78 character has the same robe armor=81. So I guess if I were at a high enough level, that robe might eventually go over armor=100.

Edit: Checked my "L78" character at a higher level, L82, and the Robe of Tribunal armor=81 (the same), so perhaps it doesn't scale after you find it, but it does scale until you find it. I guess it's best to just play and explore, take what you find and not get too hung up about it.