Thinking about getting one of these. I think I will probably land on the standard 1660.
The 1660 Ti is pretty close in price to the 2060 and the benchmarks I've seen have the 2060 outperforming it by a bit too much for my tastes even in non-RTX workloads. Standard 1660 sits nicely on the pricepoint competing with the RX580/90's and such, and does seem to have an edge on them in gaming. Performance close to a 1070 for a good bit cheaper.
And in the overclocking benchmarks I've seen had the standard 1660 gaining 10-15 fps, surpassing stock Ti performance, where the Ti would gain only 5 or so fps. Of course this could just be them having unlucky Ti's and lucky 1660's, but the pattern seems pretty strong.
The main difference between non-Ti and Ti being GDDR6 ram, I think the non-Ti gets better price to performance while sacrificing the efficiency of having GDDR6, at this price range a tradeoff in favour of the non-Ti IMO.