Personally have tried many tints, brands and styles since living in South Florida.
Llumar, 3M and Huper all make excellent films. SunTek and the like are sub-par in terms of heat/solar energy rejection...more for cosmetics, it seems. IMHO of course.
Claims of UV protection are moot - nearly all modern automotive glass inherently has ~99% UV blockage.
I`ve personally had the best luck, or shall I say found best balance of performance and price with 3M Color Stable.
However, the single biggest difference I`ve felt/witnessed regarding window films, is getting a film on the front windshield. Specifically, we`ve done our front windscreens with 70% 3M Crystalline, which made a VERY big difference in comfort of the vehicle. It`s nearly transparent, and does not interfere with driving in the least.
Currently have a car with Color Stable on all the glass, except the front windscreen uses Crystalline. And have a vehicle with Crystalline all the way around (including the windscreen). Both are identical.
As mentioned, a competent installer is KEY.
Regarding pricing - here in SoFlo, expect about ~$220 for "regular" film, and ~$450 for "fancy" film. Front windscreen extra, runs about ~$200.