The first three have semi-symmetrical wings. The Voyager??? I can't find that in the description.

The first three will have some tendency to self-correct. If you get them "cocked up" and then let go of the sticks, they'll slowly try to right themselves. That's not really a wonderful thing nor worth much if you're flying now with an instructor on a buddy box.

The voyager won't be quite that stable, but once again, if you're on a buddy box, that isn't the most important detail.

How much had you flown the first airplane? Were you getting comfortable? Were you taking off and landing?

I'm flying my own Tiger2 and buddy boxing a friend with his 4Star. Both of them are very stable and as easy to land as a couple of highwing trainers that I'm flying with guys I'm instructing. All three of those guys would be just as comfortable landing my Tiger2 as they are with the trainers or 4*. They've all got "enough" time to have become "used to" flying enough that they're now practicing, not just trying not to crash. If you're to the point where you're practicing making your figure 8s look like figure 8s and not just trying to keep from crashing, I'd suggest that you buy whatever you think looks kewl, so long as it's described at least as a good 2nd airplane. Of course, if it's described as a trainer that's kewl too.

If you consider yourself as a student that's progressing at a normal pace, and have more than a couple of flights, then don't limit your choices to flatbottom wing trainers. But if you're still "just starting", then stick with the aircraft like your first three.