My fave is Aurifil 50wt. It is fine thread, so the bobbin holds more of it, and I get very accurate seams with it. It is very lint-free compared to other cotton threads I have tried. I believe Prescencia 60wt is even better (still thin and lint-free but 3-ply rather than Aurifil's 2-ply so probably stronger), but I have not tried it yet.
I used Mettler silk-finish thread for years, but once I tried Aurifil I didn't want to use the Mettler anymore.