This is fairly easy, because everything is more aerobatic than the Nexstar!

Several good suggestions here already - Stik, Four Star, Tiger 2. My first ARF build was my Thunder Tiger Tiger Stick .40 ARF, and I'm still flying it after 3 seasons. It's an easy, straightforward build that results in an aerobatic and sturdy flier. I have a Tiger 2 that a buddy had lying around in his garage, he gave me his old kit and I bought a radio and engine for it. I'm still flying it after 3 seasons as well, and I can certainly guarantee you'll love the way they fly.

The World Models Sky Raider Mach II is another beloved low wing second airplane, and at $69.99 for the ARF it's a bargain as well. I think the Phoenix Dolphin is another design worth serious consideration. It looks like a copy of the Four Star, but it's considerably less expensive. There's also the World Models LA Racer or Super Sports, the Hangar 9 Pulse XT, the Seagull Models Spacewalker II or PC-9, the Great Planes Easy Sport ARF/Kit or Rapture 40 kit, the VMar Arrow or Ramrod, the Sportsman Aviation Sport Stik, the Kyosho Calmato Sport, and probably a hundred other ARFs and kits that would make great second airplanes.

Get yourself a runway mowed and grated soon, and good luck and good shopping!