2 vs 3? kind of a wash. 2 is a bit "cheaper" but 3 is a bit more "flexable", but even that is debatable. What isn't easily debatable is they're both good airplanes.
That whole class of design (AXN, Skysurfer, Bix 1/2/3, Explorer . . . ) tends to be very friendly to new pilots and good planes to go out and just fly. The 2, being a belly lander, is a bit less flexible for touch-n-go's on all surfaces, but should land well anywhere, and both are small enough to hand-launch. The cockpit and fuse layout is a bit more accommodating in the 3 than the 2, but while it's a building challenge fitting elaborate setups in the 2, it's been loaded up many times in clever ways -- not as easy, but not impossible.
Only big "this v. that" I can see right now is availability. I'm assuming with your quads you have your own radio gear, and I don't see a PNF (only needs radio and battery) Bixler2 for sale at HK in any of the warehouses. The ARF (needs all electronics) for either is for sale in the some of the warehouses -- not a bad option if you want to spec your own power system. Alternatively they're both available as RTF (needs nothing) at various warehouses, but the junk radio they ship with it is . . . well . . . junk.