Feltrinelli is on Garda, not Como, but it is lovely. Passalacqua truly is the best hotel in the area now, and it is much more "boutique" than the other's in the area. Have had several clients here with perfect stays and I have only heard amazing things from others who have stayed. It's an extraordinary property.
Villa d'Este is not worn out, and I believe they just did some updates, but where you stay will make or break the stay. You need to be in the Cardinal building.
My big knock on Tremezzo is how you need to cross the road to reach the pool (which they conveniently leave out of any photos online).

Personally, I rank Passalacqua > Villa d'Este > Tremezzo & Mandarin.

If you are traveling with friends - Il Serano has a private villa that is supposed to be phenomenal, and the booking policies are surprisingly reasonable.