We've been to both. FoF is interesting. I really enjoyed looking at the variety of aircraft although it's a bit 'tourist theme park' in some respects. The EAA museum is a bit more to my taste: Put the stuff on display & give me lots of information. Not saying that FoF doesn't but the diarama stuff isn't my thing.
If you drive to S & F make sure you arrive *early*. The car park fills quite quickly, leaving a trudge & queue to get in. We arrived about 30-60 mins before opening and parked right at the entrance.
Flying in is really fun. Don't fly in too late in the morning or all parking spots on the accessible side of the airshowdisplay line will be taken and you'll be parked a *loooong* way from anywhere + will not be able to access your aircraft until the airshow is over. Only after the flight display ends are you allowed beyond the line to pre-flight & go - hence early-ish arrival so you get parked on the accessible side.
It's a real scrum to go once the whistle blows. Handy if you've already been able to preflight and are sitting there ready to start. Still will have a long taxi but the volunteers & ATC are very well organised. Be patient & follow the directions.
There's a NOTAM about S&F procedures that explains things. It's really not that hard but you can't be slack about things. I found it a fun & enjoyable challenge different from my usual flying. My wife loved being a pax up front and seeing how it all worked.
Her biggest impression was the scrum to leave: It's just like the end of a large sporting event only with aircraft instead of cars.