Sergeant was actually a good rank, but I would have loved to have made Warrant Officer before I got out.
In the CF, I think CWO/RSM is the best rank -- God of the NCM's as it were, if done right.
I mean a good officer is a good thing, but a good RSM is worth a regiment of good officers...and will protect you from the bad ones.
Some Sergeants and Warrant officers I know refused a commission-from-ranks because it meant a promotion to Lt -- and they considered that a demotion. Plus you had to go to officer school to earn your stripe; most Sgts and WOs were at the top of their trade and never had to do career courses any more, and didn't want to restart (I'm only referring to the Comms world here).
At least an MWO made Captain, which wasn't too bad.