First off, Treach is one of the best of all-time.
I still say Naughty's best album is Poverty's Paradise. And if you actually listen to Treach on that joint, he's miles ahead lyrically, from where he was on the debut album. He was at his peak in '95. Dude was always a stand-out MC. If anything, I think being in the group is what gets him slept-on.
There was a lot of talk about him doing a solo in 2000, but who knows what happened with that. That said, he's never been on Redman's level. Two different types of MC's, but if you take Treach's run from '91-'96 and compare that to Reggie's, it's not even close. There were very few MC's better than Redman during that stretch. And the ones that were better, were making some of the best albums Hip Hop has ever seen.