exactly, that means Kenpachi was stronger, yet you named that a victory for Ichigo
you seem to misunderstand Kenpachi's principles.. he ditched the eyepatch because he thought Ichigo was worth to do so, actually he wasn't
Kenpachi would have killed Ichigo easily without the mask-protector or by using Kendo at that moment, but he didn't, he isn't in for the kill he just want as much fun as possible.. Ichigo wasn't as much of threat to him as Noitorra was later on. I don't get why people think so low of Kenpachi, please reread those chapters and you will see that Ichigo barely got away with his life thanks to Kenpachi's principles. Is it this "the winner takes it all" philosophy that let you get the impression Ichigo walked through Kenpachi???
Grimmjaw defeated a whiny Ichigo who was afraid of even using his bankai. Ichigo only did so because Rukia got fisted. Later he immediately put on his mask because Kubo gave us the drama instead of some logic. But ok, it would not have been as exciting to see Ichigo keeping up with Grim in Bankai state, so he let him put on his mask immediately. After the mask broke he suffered the side effects and therefore was no match, it gave an dramatic impression and thanks to it everyone thought the bankai alone is worthless from now on
. In their final battle he only switched into Vizard mode to protect Orihime from the gran rey cero and was clearly stronger than Grim, this wasn't a tight win or something like that, Ichigo wasn't half dead like he was after fighting Kenpachi, Byakuya or Ulqiorra. Sadly Grimmjaw is just another Renji. That means an Ichigo with his hollow under control only needs his bankai to deal with unreleased Grimmjaw.
Why would Noi be superior? Ichigo had no chance to use his mask against Noi and took quite some damage before, so there's no accurate basis to say that. In fact Ichigo will somehow manage to defeat Ulqiorra, although I don't think it will be nearly as clear as the Grimmjaw fight.