I have only ever flown TK economy for a short IST-MUC flight but have friends and family who have done long haul in Econ as well as business and overall their experience was fine. The only negative I’ve heard is that they aren’t great in IRROPS situations but maybe that less of a concern if you are flying business.I agree it’s probably better than Air India based on anecdotal evidence.

If you want to maximize points and such by going the TATL route from Vancouver, you can also look at adding additional hops e.g. AC to Montreal or Toronto, then TK to IST-BKK or some other such routing.