It's not that simple, unfortunately, because the issue is very random.
There are loads of wonderfully run airports. Ljubljana LJLJ, everything in Croatia, Sitia LGST in Crete, Cannes LFMD, St Yan LFLN, LTQ of course LFAT, Prague LKPR, Biarritz LFBZ, etc etc.
I've been to airports which are bigger than Gatwick (in runway size, etc) and which are totally straightforward, and cheap.
In Greece, they vary quite a bit. None except Athens LGAV are particular pricey, but the bureaucracy varies a lot.
Back here, Cambridge, Newquay, Leeds, some others. Not always cheap but efficient.
The sh**s are well known from these pages
Norwich comes to mind... 2 yellow jackets confiscating my toothpaste and having a good laugh about it. But on other occassions they have been fine. Not cheap but fine. There seems to be a "personnel issue" there.
Zaragoza in Spain and Padova in Italy have been both good and totally atrocious, on different occassions. Italian airports are an organisational pi55take and are best avoided and as a result most of their GA seems to operate from strips, on mogas. But Trieste was excellent. Tirana LATI was really crap (it's run by British management).
Like I say - very random.
You get a feel for it when communicating with an airport.
Back to my JAA IR "90% bollox" study