The best tape I have found recently is 3M stuff, but from industrial suppliers, it is a much better quality than you get in the shops / DIY stores, decently strong and an adhesive that is just right to stay in place but still peel off. I cannot remember which one it is they use (3M do various different types and grades) I seem to recall it was the 501 grade, but would not swear to it. They also do a low tack versions for use in more delicate situations.
I am really waiting for Gorilla to start doing masking tape, I find all of their other stuff good and their version of duct tape is brilliant (unless you ever want to remove it!)
+1 for frog tape, works well, but anything left on the shelf for ages s going to lose performance, guess thats why frog tape come in an air tight container..
A good test when buying masking tape is to press into the outer edge of the roll of tape. It should feel soft & spongy, if not it is either cheap rubbish or old stock that has gone hard.
Lidl has the std 3m tape in stock regularly & it's pretty good stuff.
I tried buying the blue tape locally, none of the body shop suppliers stocked it. The only place that had it was screwfix at an extortionate price!
One to avoid is Aldi's own brand. Some of their stuff is good but the masking tape is very poor quality, and tears into strips too easily. I also found their knock off Dremel accessories are really poor - the cutting discs shatter if you look at them funny.