Should i keep my 2006 mustang gt or trade it for a subaru impreza wrx?

So im thinking about trading my mustang for a wrx or sti. I've had my car for about over a year just its giving me the problem of going through alternators. Ive gone through 4 alternators and its getting annoying that in a year i have to replace it. My car is so much fun i love the v8 power but i want to see if people have ever gone from a mustang to a wrx. Can anyone compare both of them so i know if i should stay with my car or trade it for a wrx. Iooking at 2006-2010 wrx. I have a 06 mustang gt 5 spd. 120k miles