RE: best first time plane for 50cc?
World Models Extra 300S
Mine is 15.5 pounds RTF with empty fuel tank. G-62 on the firewall.
It needs a few very minor mods--to really get it really tweaked in, but nothing you can't handle in an afternoon of work.
Flies like it's on rails. Flies lihgt. No over-rotation in snaps and rolls. I can't say if it does 3D well--I"m too scared to try it with mine. It will flat spin till the cows come home--both inverted and upright. Stalls are soft and gentle--mine drops the nose slowly and then the right wing goes a bit after the nose is already pointed down. Easy recovery with a few clicks of power and neutral sticks. Soft and gentle on the landings. Great glasswork. Double-beveled control surfaces with metal hinges.
I really like mine--just don't get the chance to fly it enough.