I'd suggest to anyone the C-172, but since I own a C-152 and conduct usually all of my training (I give cheap rentals out to my students) in them. I do how ever prefer a C-172 but I cant afford one, and the C-152 was a handy down from my uncle who sold it to moe for 700 Dollars (yep thats right) because he couldnt fly any more (getting old-heart problems). If you're gunna do training though, unless the rental is to high I'd suggest a C-172.
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.