For me the fun stopped in the US after 9/11. TSA and airline voodoo economics finished the US fun side.

Some places remain fun for me. Much of Asia is still fun flying.

I enjoy CX, QF, EK and a handful of others when they are nowhere near the US or the UK. SU is fun, albeit with a slightly masochistic ground experience in either Moscow airport.

I enjoy domestic flying much less but in a few places even that is tolerable enough. The big fun-lost quotient for me is not the equipment but the security and ground services, coupled with disgruntled crew.