I offer Zaino as an option. I've only used it on 2 cars other than mine. One was a riced out Escort that won all kinds of awards at the car show! He was getting it detailed for that reason - and opted for every conceivable option!
Anyway - I love Meguiars as well. That's why I use it on customer's cars. I haven't had any complaints.
Both get thumbs up imho.
I've used P21S before on a customer's car and they loved it. However, I think I phugged up and left it there (brand new jar). They say they don't have it (yeah right) but whatever. I haven't had time to get another jar.
I really want to use it on my car....I've heard great stuff about that - use it as a top coat(s) and it's unreal.
I'd love to try it on my car since it's black.