My fav's are the 727 and 707 just because they are planes you actually fly ( what a concept). It's very satisfying landing the plane by hand in 1/2 mile visibility. Lots more fun than imputing a few things in a FMC and staring at the screen watching it fly itself.  The 727-100, in spite of the bugs, is really great to fly on shorter routes and handles like a sports car. I must admit I cheat and bumped up the thrust a bit though.