Wow - 90 types flown. Now that's what I call a statistically significant sample ! On the other hand, if one had flown only one type and it was fun I guess that's an automatic ten :)
It's tempting to go all reductionist and start analysing the components of a fun as opposed to a not-fun flying experience. For, example, it certainly helps if one is confident enough about engine and airframe to not be flying in a perpetual state of angst (as opposed to a healthy alertness). Also, control harmony, responsiveness - a feeling of integration with a well designed machine, good visibility etc etc. Overall, I feel the best description of a fun aeroplane is one that is easy to fly - but hard to fly really well.
Whoops there I go slipping into reductionism again whereas it's really more interesting to know which aircraft people find "fun" whatever the individual and diverse reasons may be. I don't have enough types to make a meaningful table so will just contribute a few thoughts:
1. My Foxbat was a happy choice as it ticks an awful lot of the boxes - 8s and up all round I figure.
2. I loved the fighter feel of the Alpi Pioneer
3. From all reports (not been in one yet but it's coming) any well tuned RV 6 -12 is a silly grin generator.
4. Every LSA I have been in beats the low end Cessnas and Pipers I learnt in by a country mile. RA has been a revelation to me.
5. One exception to the above: For a little while I had access to a beaten up C206 which I flew mostly on my own - what joy to feel the kick in the back and hear the growl on opening that up and the, for reasons I can't explain, I got an enormous kick out in turning around in the climb out and looking at that great empty space following me up into the air !