Anything with complex management of big combustion engines and steam gauge IFR equipment is good to explore the world in MSFS. Something like a basic Sperry autopilot is cool, too.
And complex / technically special planes like the SR-71 or the Concorde. Would love the concorde with PMDG or A2A like system management. So, something like this:
Bombers for there more complex systems (B-17, B-24, B-25, Lancaster)
Bf-109G (With proper sound and engine handling)
Constellation (any type)
DeHavilland Comet or 707 for a steam cockpit Jetliner
SR-71
Concorde
Probably some I have forgotten.