If you're serious about getting started in 3D, pay close attention to the advice given by XJet and JustErik.

My first "real 3D plane" was a UCD 60. While it was OK for learning to hover, it was terrible for learning to harrier. Since harriers are a staple maneuver of basic 3D flying, the UCD 60 is a handicapped 3D plane right from the start.

I've briefly played with the UCD 60 on G4. The simulated UCD 60 is way underpowered, but it still has the same sloppy feel in 3D flight as the real one.

I'd suggest trying some simulated 3D practice with the Yak 54 3D on G4. This plane closely simulates the feel of a good profile 3D plane, such as a Mojo. If you prefer the feel of the simulated Yak 54 3D over the simulated UCD 60, then you will prefer a profile Mojo over a UCD in real life.

I know that this thread was about good 3D planes from Tower, but Tower doesn't really have anything to compete with a Mojo when it comes to 3D flying.