I have only seen TARCan, TARAus, and TARA season 5.
I think TARCan is good but the seasons start to blend together because of how Canada heavy it is, but I usually enjoy watching them. Even though it is mostly Canada, the tasks are usually great! I would love to see more abroad, but if budget constraints/sponsors do not like going abroad, I still will enjoy them!
I watched TARA5 and that season was great and I enjoyed it a lot.
Of what I have seen, I would still say that TARAus was/is the best franchise. I feel like every season was phenomenal and very entertaining! TARAus2 in my opinion is the best TAR series in all International versions (including US). I wish they were more easily accessible, so that I could rewatch them. I feel like every season they have made has been great!
Random question, is TARChina in English? (Not sure where to ask, sorry to go off topic)