I didn't use Tabnine but anecdotally heard it is not as good to guess whole methods the way Copilot is. Now I understand why.

The only suggestion I would make, maybe lower the price, MS is bigger player, they pretty much set the standard now, if they have lower price even symbolically, it would hurt you more.

I personally am happy with Copilot, had some really wonderful moments and savings in time searching for proper method syntax is where I get a lot of benefit. I should spend time to get to know Tabnine as well so not to be ignorant on this new technology.