Others may disagree....
First question - what's the cars lifestyle daily driver or garage queen?
If the latter you may want to go the extra mile, the former, well the law of diminishing returns sets in sooner.
Lets assume you wash (2 bucket) every week/every other week, clay once/twice a year, polish with a generally available good quality product but not into £100 a pot specialist product...
I've tried several, ones I stuck with the most Autoglyme SRP and EGP and various Meguiares products. However we're a one car family so I've never been able to do two cars with different product and compare results I've obtained back to back.
TBH for a daily drive I think the differences are small. So what's my current feelings?
The AG SRP is good at shifting those stubborn bits of dirt that washing doesn't move.
Like the AG tar spot remover, great product.
AG SRP is better with a machine polisher then by hand but you'll still get fine results by hand.
Liking the AG EGP - easy to apply/remove
Last Sept got a tin of Colinite 915 liking that and with the EGP still doing its thing now.
Megs tyre dressing - applied with nail brush but it doesn't last long, not found a tyre dressing that does last more then 2/3 weeks, much less in bad weather.
My car isn't perfect its got swirls that I've never seriously tried to remove. But I get folks commenting entirely un-prompted that its the cleanest car they have ever seen.
One product I've used that really did impress me. A glass polishing kit off Amazon, Windscreen Polishing DIY Repair Kit - Car Glass Repair
https://www.amazon.co.uk/dp/B00ADMA8GQ/?tag=amazon0e9db-21
Took me a while to figure out that there was something on the windscreen and washing/clay/IPA/solvent based product wasn't shifting. Tiny bit on the supplied pad on the end of electric drill shifted it and wow did it make a difference.