I'm going to say DG 253.
A close second may be Optimum Car Wax (OCW) spray.
Both of these are dirt cheap, and they always give excellent results year after year.
You know, Paul.
There is something about Optimum.
Their products are super easy to use for the most part, but for me there was a pretty huge learning curve. I feel that some of the poor results people get with them is more a result of a mis communication with the manufacturer.
I'll use Opti-Seal as an example.
I've had the same bottle from about 2015 or 2016. I really wanted to like it, but I never did. It reminded me of Turtle Wax Ice Liquid Polish, the clear stuff they released in 2007. I had a difficult time with that stuff too. I had issues knowing how much to apply, how long to let it set, etc, etc.
With Opti-Seal, I thought applying with a foam applicator was not what I wanted to do, so I sprayed directly to the paint, and wiped with a standard terry weave microfiber. It never looked like it was protecting the paint - with neither the water behavior, or the look. So I made myself try the foam applicator. Same thing.
Over the summer I discovered that Opti-Seal really liked a surface that was polished with one of their polishes before hand. This left me with great water behavior. My mom's car was done with Hyper Polish / OOS in August, and still looks great, even as she uses the in bay automatic touchless to wash it.
But just last week I think I found yet another way to go about it. I had a bad habit of applying OOS without it leaving a wet film behind. I don't think that left enough active ingredients to get the product to work right. The next thing was that I wiped it off to soon afterwards, and/or got it wet too soon after application. So I hit the pad with one spray, and applied it until the film was getting weak, and then added another spritz, and so forth. The next thing I did was wait for most of the film to flash until gently wiping with a TRC Pearl. Then I kept the car dry for an hour or so. One morning I applied OOS to my gf's windshield, and she said it sucked. I applied it like how I'm describing here, and she loves it!
So even though Optimum products are super easy to apply, sometimes it takes a minute to truly "figure out".
And I have to say, I absolutely love Optimum Car Wax. It was all I used to protect our cars summer 2021. I have a picture of it fighting off a bird dropping on my car. Opti-Seal on my new mower keep the dust way down on it. If I could get away with just having that as my sealant, I'd be a very happy man!