Forester: I own a 2001, and have owned a 1998, 2000, another 2001 and also a 2004.
Impreza: have owned a 1998
Legacy- have owned a 1990, 1991, and 1992.
Forester- 1998 was a bad year with the Dual Overhead cam.. i would avoid it. The 2000 and 2001 that i owned were only plagued with the failed head gasket. The 2004 is leaking at the head gasket and has the piston slap.
Impreza- EJ22 is bulletproof Made in Japan.. good bang for the buck.
Legacy- My 1990 was much better than the 90 and 91. 1990 was made in japan, was built like a tank. 1991 and 1992 were not that desirable to me, stuff fell off inside, had alot of sensor issues, wheel bearing issues etc.
I will stand tall and say that i think Subaru Foresters in the 2000-2002 with an EJ25 phase 2 engine with head gaskets repaired are nearly bulletproof.
Avoid- EJ25 with phase 1 engines, avoid engines with piston slap at cold startup (this is unproven to deal with reliability though).