Hi,
I think it depends on what type of virtual flying you are interested in doing.
If you're interested in flying larger aircraft and move up to the "Big Iron", I'd do the following progression:
- Cessna 182s - introduces constant speed prop, slightly heavier and faster. Perhaps learn some IFR flying as well?
- Piper SenecaII - introduces twin engines, more complex systems
- DeHavilland Twin Otter - turbo-prop
- A320/777/707 - multi-engined jets
If you're interested in historic warbirds:
- Piper Cub - introduction to tailwheel aircraft
- Stampe - slightly harder to handle tailwheel aircraft
- SpitfireII - more powerful, but still fairly simply
- P51d Mustang - more complex systems
If you're interested in military jets:
- PC-9M - Turboprop trainer. Introduce more complex systems (retractable undercarriage), much faster, turbo-prop.
- Alphajet - Faster again, jet.
- F-15C - full military fighter jet
- F-14b - carrier-capable jet.
I'm sure there are some other "pathways" as well.
If you take the time to really master each aircraft in turn you'll be a better pilot in the long-run, and you'll more closely mimic the progression that pilots make IRL. If you jump straight onto a 777 or Mustang from the 172 you'll likely struggle with the combination of more complicated systems and different handling characteristics all at once.
I should put this on the wiki somewhere. In fact, even better would be some sort of "choose-your-own-adventure" style map which would suggest another aircraft based on what you're flying at the moment and what kind of flying you like to do!
-Stuart