Stability is a much more complicated issue that high or low wing. Dihedral adds stability, so a low wing plane can be just as stable as a flat high wing plane. But there is more to what makes a good second plane than high or low wing. Tail area is a big part of it, with bigger tails (like with ugly sticks) weathervaning into side winds more and being more directionally stable. Then there is stall behavior; a plane that drops a wingtip will get wrecked fast by a beginner.

It's hard for us to tell you what to buy because we don't know your flying ability or teachableness. The Hangar 9 warbirds are more sport plane like than true scale like, so plenty of people have flown their P47 as a second plane or first scale plane. But it won't be as pilot friendly as a 4 Star or Goldberg Tiger 2 or 3.