Chances of middle seat J have to be pretty small right now, You can pick your seat once ticketed, lowering risk further.
777/330 J seat is excellent - despite claims from bloggers.
Soft product is another matter. TK was always weak save for great catering, now thats gone you are basically paying for a bed......and if Y loads are low you might get poor mans biz (empty row) anyway
Due to the restriction of the USA ( non-USA citizens could not board a flight from mainland Europe or UK to the USA - some exceptions apply ), the loads for TK flights are pretty high in Economy Class on the USA-Turkey route.
Plus, when India re-opens their borders, those flights would get much more full than it is at the moment.
I also agree that the 77W/333 Business Class seat is great and comfortable, especially when you don't have a neighbor.
And, it's true that the tax difference and the mileage difference for Business Class would only be for the hard-product.
For the OP;
The only US destination that TK has an open lounge at the moment is Washington-IAD; if you're planning to fly USA-IST, in other US outstations, you would not get lounge access other than a United Club.