Many similar threads can probably be found on this general topic with various experiences. My 2 cents:
For long-term coating option may also want to look at Modesta such as BC-04 or BC-05. There is a relatively recent Youtube out there you can easily find showing Modesta over Suntek PPF and demonstrating alleged non-interference with self healing properties (coincidentally on a Model S). First such test I have seen of that coating over the film. Modesta is relatively newer glass coating in U.S. and just gaining more popularity. Until few months ago, couldn't get it here. They have a primer/polish P-01A that can also act as a last-stage prep or a repair. Designed to help in particular for cars with history of a lot of polishing and little to no clear coat left. Last year I also found some article (I think Australian sourced) about a test of fireworks damage on various popular glass coatings. (I know, a little off the wall but an interesting test of a coating). Modesta was pretty obvious winner there.
I have done a lot of research for literally a couple years (though gave up and laid off of it for a few recent months) and there is no magic solution but a LOT more options now with coatings than there were couple years ago. My biggest problem originally was nobody was installing Opti Guard when I wanted it. When I finally installed as a test on my other car it did not perform as I would like because it is not super slick.
Experience and skill of installer with many of the coatings is key so finding the person who installs the coating you want in YOUR AREA is sometimes a challenge until the particular coating gains traction in the marketplace.
Also considerations probably include how long you plan to keep car. If just 3-5 yrs, much less to think about for long-term effects of either PPF or coatings.
PPF - 3M/Scotchgard has historical problems with removing adhesive after being on paint for very long. Apparently the adhesive formed a stronger bond to the paint than it did to the film. Depending on environmental variables, can be a nightmare to scrape off it left on paint too long (not cared for, too much heat/sun etc).
Suntek been getting more respect last couple years and rumor is the adhesive is "less aggressive". Again, installer experience and skill are key to what you select.
VERY FEW coatings can go under the PPF (because film will not adhere to most). PPF installers will tell you nothing can go under it. OptiGuard/Coat supposedly can (because not super slick) and, frankly, that's the only place I'd put that coating is under a PPF that can protect against debris strikes. I personally think it makes the surface more susceptible to chunks of paint coming off when a strike occurs due to the relatively grabby nature of the coating. That's why it never went on my MS. I don't want to pay to put something on that just makes my greatest worry bigger. I can wash my car and there are a lot of good rinseless washes out there including Optimum's ONR and ONRWW, among others. I just cannot protect against debris strikes.
Problem with putting true coating under PPF is timing of installation. Most require a cure period. While the Opti-Coat formulation (consumer vs pro) has a shorter cure period supposedly, the Opti-Guard probably has to cure for at least a week or two before you can consider putting anything on top of it. That's what I recall. So big coordination issue there. In my prior quest to find any coating that could go UNDER the PPF I found only a product out of the UK (available to purchase) called Max Protect UNC-V2 (almost exactly a year ago). They said with min 20c temp it fully cures in 6 hours.
In terms of "sealants" vs true "coatings" I would say Menzerna Powerlock is excellent based on everything I have read and heard from pro detailers tests and experiences.
For me biggest challenges have been finding sufficient test/experience data for a bit longer than the initial application (everything looks good when first applied), and then finding the people who do what you want, with what you want, in a location that is accessible. Some great detailers out there over the country but just sometimes geographically undesirable.
Products are always changing and by the time you get a little data under the belt, they are moving on to using something else. Nature of the marketplace I guess.
p.s. in my opinion, you are NEVER going to have NO RISK of swirls. Washing technique will remain important no matter what you put on there. Even the glass coatings and the PPF will get some swirls if care is not used. However, I do think that making things stick less and making the washing easier will naturally reduce the risk dramatically. I've been using Optimum No Rinse since last year, have had only 2 other pro detailers wash the car on 2 occasions and I have not induced any swirls or scratches from washing using that product. However, I may be more careful than the average car washer too. I also think Optimum products tend to have a little more eco friendly formulations than some others, which is important to me.
Bottom line for me is I haven't found anything yet to make me want to pull the trigger on extra $5k to $7k of cost just to set myself up for a "different" kind of problem with PPF adhesive in 3 to 5 yrs. Right now I still have the factory Nano Fusion partial kit on the car and besides wash/wax maintenance myself that's as far as I've gone although at some point I'll have to decide on removal and replacement strategy.
To help further clarify for anybody stumbling on this among similar threads...every wax, sealant, coating and film product is designed to be a sacrificial barrier to take some kind of abuse away from the paint. At the most basic level, to protect against exposure to the "atmosphere" such as oxidation and UV damage. More sophisticated coatings will protect against more caustic and aggressive "pollutants". None of these are really designed to last "forever" although some will last quite a very long time. Most of the coatings are there to not only take the initial abuse, but take the polishing abuse so you don't end up taking most or all of your factory clear coat off the car. Even the PPF, designed to absorb more of the "mechanical" abuse, is not really designed to stay on the paint "forever" so don't concern yourself with "lifetime" warranties. For a garage queen maybe 7 yrs is okay but most cars driven/parked out in the heat and sun I'd be afraid to leave on more than 3 to 5 yrs. So if you plan to keep the car for a long time and are planning to use an arsenal of protection that includes PPF, please be aware that you will most likely want to get that PPF replaced "at some point". When, will probably depend on exposure to elements, heat and general abuse.
