I would not presume to make a recommendation about which motor mover is the best, but I will point out that of the two generic types, i'e, jockey wheel replacement or A frame mover vs main wheel mover I strongly advise against the A frame type for reasons of safety.
The grip a mover has on the surface on which it runs is determined by the force with which it is pushed down to the ground. Effectively this will be limited to just about the nose load of the trailer, which is unlikely to be more than 100kg. This roughly the equivalent of an adult. If an adult feels they can't control the caravan, then the a frame mover will be having very similar issues. Its not so much the ability to get the caravan moving, but more teh ability to stop it once it is moving.
By comparison the main wheel movers have roughly half the weight of the caravan on each wheel and will as a consequence be far more sure footed.
As the difference between makes of movers. None of them very different in any way that is likely to make one make more reliable than another.
Don't base your decision only the apparent fact that one manufacturer has an outstanding after sales service - whilst that is possibly a comfort, it in no way necessarily means their product is superior, in fact i could mean their product is less reliable hence the need for such a good after sales system.
It could also be that other manufacturers are just as good but don't shout about it as much, Or it could mean that other manufacturers product don't fail as frequently.
Whilst I may appear to be critical of one manufacturer, i'm not - it is their level of service that others should aspire to.