KO servos are excellent. But I think Futaba servos are more hardy. But that's just me.

Digital versus analog? Digital draws more power but more accurate, generally faster, better centering capabilities and have more holding power. Analog servos are not bad either. If you get good ones, they can be fast, accurate and have good holding power too. They are very good on the receiver pack consumption too.

Generally, I would go digital on steering and a good analog on throttle / brake.