Gangtok was such an amazing place. It is so much under-rated (J&K is very very much over-rated). People are very friendly, prices are reasonable (considering it's a Hill Station), good food, great scenery. Go for it bro, you will love it.
Whereas Darjeeling is kind of OK OK (comparing Gangtok). Crowded, costly, but still much much better than say J&K, imho.