Filtration is important.
I-20 is top of the line in reliability and features. It is a commercial grade head. It has a stiffer retraction spring than most residential heads, so it's important to have that 45psi at the head. It does carry a stiffer price tag also. Well worth the price, though. The PGP Ultra comes in second, with a lower price tag and lighter spring than the I-20. The PGP Ultra carries a lesser warranty, also.
The 42sa's seem rather reliable on municipal water applications, but can't comment on pump applications.
I manage a few townhome complexes that have well over 300 I-20's installed on each site, and it amazes me how few need replacing each spring. After maintaining these sites for 5 years, I can count the number of heads replaced on two hands. They are an amazing head. But, like any head, dirty water will shorten their lifespan.