I've been playing roguelikes since c. 1990.
I've just beaten one for the first time.
Brogue spoilers below the pic.
Brogue: Enchanted plate armour up to its final value, then staff of lightning from [2/2]. Had an ogre trained up with Protection for a while, then lost him, rescued a Tentacled Horror and finally got him to eat a Dar Priestess for Healing, after bouncing him off everything else. Polymorphed every dragon I saw, had more than enough healing/telepathy/magic mapping for the final few levels. The only times I really felt threatened was an out of depth flame turret across the level which I jumped into a chasm to avoid, and when I ran into my first Dar battle pack torturing said Tentacled horror. Of course, when I read an unidentified scroll to try for options, and said scroll was summon monster and it didn't materially impact the situation I was in, I knew I was pretty good for a victory.
Verdict: Plate armour in brogue is probably OP. The seed I had was definitely OP - three stacks of javelins in the first few levels (two in the same room), and it just persisted in throwing plate armour at me.