My play ground.....!
Out of the 3 in Torbay, Brixham and Torquay have the easiest slips to use, and plenty of parking, BUT, all car parks in Torbay are bloody expensive. Brixham slip, you can get away without paying for launch and recovery most of the time, as, due to funding, no wardens on duty, same as Paignton. Torquay, you will have to pay every time, as the main Harbour Masters office is there.
Paignton does dry out, but is still usable. The sand is hard packed and can be driven on. Not so much parking, but same rates if you use the car park, but more back roads around the harbour where you can park car and trailer together, and not get stung for trailer fees aswell.
Totnes is nice and scenic, but you are restricted on the river with a 6 knot speed limit, and is quite a trundle down to Dartmouth (8 miles) to the open sea.