If the Tunnel is pretty handy, then it is the best option. Not so clear cut when in Scotland though.
I quite like the DFDS Ferry (opps - "Mini Cruise" if you don't mind) but never taken a vehicle on it.
Used the Ferry with a vehicle from Dover before the Tunnel was done and that was ok, as were the Ferries from Poole, Holyhead and Pembroke, so all options are ok to me.
I did do a Hoverlink once to France (just a there and back booze cruise) and that was insanely rough - I'm not sure now if that one carried cars as well but I bet if it did they would have have to be super-securely strapped down!