Meguair's #21 kicks the piss out of Zaino and so does Klasse HGSG.
Also, 99.9% of the difference is how you use what you have, not what you use. Some peopel swear by Mother's, some will tell you Meg's is nothing but snake oil and then there are those will ONLY use boutique products. A lot of it is preference. HGSG, while a MONSTER pain in the ass to deal with, gives a high-gloss, slick, durable finish with great shine. #21 isn't nearly as slick but has amazing depth that I can't get with anything else.