You don't find many of the little Grumman's around. There was the Trainer, the TR-2, and the Lynx. They are cool looking 2 seaters with no doors...the canopy slides back just like a fighter. They have small wings and so they have higher landing and stalling speeds compared to a 152...I would say they are less forgiving than a Cessna. I don't know of any schools that use them as trainers but they would make a great little personal plane and if you bought one there wouldn't be any reason you couldn't learn in it.
The Skipper was a short lived Beechcraft trainer. I know of only two schools in my who state that use them. They look exactly like the Piper Tomahawk but are probably better built....typical Beechcraft quality. They are a pretty rare aircraft.
The Tomahawk was Pipers answer to the 152. I've never flown one but some people don't like their stall/spin characteristics...they say not as forgiving as a Cessna. You will occasionally find a flight school running Tomahawks, but not many.
Both the Grumman and the Tomahawk can be bought for under 20K. The Skippers are more expensive, in typical Beech fashion.