303 is my choice. Started using it day one on our new 1991 Zodiac futura - and it was still in great shape when I sold it in 2016!. Mind you, the Zodiac was stored inside heated storage in the winter, under cover. So that certainly helps. And it was covered in the summer when not in use during the week. However, the 303 cleaned and protected those tubes!
I follow that same routine with my new Zodiac 310 RIB. Every 3-4 weeks it gets a wipe down. Love that stuff...