As you say Joan, it depends. On lots of things, like
- which model of each type?
- which engine?
- what covering material?
- what do you want to do with it?
I've owned a Standard Xair with a 582, a Thruster TST with a 503, and a Thruster T600N with a Jabiru. I also done loads of hours teaching in various Xair Falcons with Jabiru engines and T600s with 582s. They're all fine aircraft/engine combinations and if I was starting out again I'd buy any of them as long as I was happy with the condition and price of the individual aircraft - much the most important thing imho.
Xair- really good with the 582, a bit slow and thirsty, undercarriage very forgiving and good for rough strips
Xair- Falcon good with either 582 or Jab. The flaps don't really add much. Ailerons controlled by cables (unlike the standard Xair) which are a pain and sloppy. Very heavy to move by hand on the ground (not sure why this is, but they're very awkward CF others). Same good undercarriage and fly a bit faster.
Thruster - lots of different types but the T600 is good with either Jab or 582. Faster than Xairs. More durable covering material. Slightly easier to get into but the seats are uncomfortable. Good rough strip performance again. Not really room or weight allowance for baggage - Xairs better in that respect.
Worth pointing out that Xairs are kit built, Thruster is factory. Among other things that means things like instruments and overall finish can be very variable in the Xair but standardised in Thruster.
I could waffle on loads more, but time for someone else to chip in and tell me where they disagree
