Q: There are a few C420 manufacturers, which one is the best?
A: Zim is the most popular by a significant margin. That said, for the most hardcore sailors, there is a cult following for the PS2000 version. LaserPerformance has been making a 420, but due to supply issues, we haven't seen any in many years.
Q: Why is the C420 still used in programs and learn to sail?
A: Inertia I guess. Lots of old sailors who run programs fixate on the boat - so, we teach kids on 40+ year old boats. You can probably tell, we aren't huge fans of a sport that uses such outdated equipment. That said, lots of programs have them, coaches are used to them and as program directors always say 'you can't get fired for buying a 420'. It's just sort of the lowest common denominator, so, we still have to sell them.
Q: Is it a good family boat?
A: If you want an ancient, heavy, non-user friendly boat that is complicated and doesn't fit two adults well... sure. Otherwise, pick *anything* else.
Q: What is an i420? Is that different?
A: Ugh, it's a lighter and more complicated 420. Not a fan and no idea why people are into boats like this.