I stayed in Falmouth when I was in Cornwall last year, and I really liked it there. It was convenient to a lot of places. It was large enough that there was plenty to do, and it made a very good base in my opinion. And most of all, it's easy to drive a car in and to get close to your hotel.
It is also big enough to absorb the crowds that you will find in the summer in Cornwall. Port Isaac will be overrun, and the Lizard probably will be as well.
So that would be my choice. But a lot also depends on where you plan on going to in Cornwall. I would make a list of the places that you really want to see and figure out what's a good base for those.
If you're going to be there for more than a few days, you might want to move to two separate bases. That's actually what I did. I stayed in Falmouth for my time in Cornwall, then when I was touring Devon, I moved up to Plymouth.
Of course, there are other places as well. But I do think in the summer you'd probably be better off staying in a larger town rather than one of the quaint villages on the coast. That's my opinion of course. 😊Regardless, Cornwall is a beautiful area, and I really enjoyed my time there.