Hello EB78user,
Starting from the assumption that it is always better to spend a few dollars more to have good quality screen protectors, in my experience I have always used Spiegen screen protectors and covers (but there are many other valid brands on the market) since my first iPhone in 2009 and I have never had any problems; before reselling them or giving them to friends and relatives, after 4-6 years, I was also able to remove them without difficulty or damage.
As for installation, if you are afraid of not being able to mount them correctly, there are many specialized shops (often also in supermarkets) that specifically carry out this activity in a professional manner.
Regards
Giulio