Rotterdam is a real field with instrument approaches and you get mingled with the 737s which they really nicely. Its about 35 minutes by car from amsterdam.
Hilversum is a true grassstrip field with 600m runways and a nice atmosphere. About 25 minutes from amsterdam.
Lelystad is the busiest ga field. Uncontrolled and on a nice day really very busy. So busy that I fiend it very dangerous. Its about 35 minutes as well. Landingfees are a bit more expensive than Rotterdam but at Rotterdam you pay atc charges €13. At Lelystad you do have some very cheap aircraft at rental stations and clubs