Which one is better VAS or Core network department.

hello!
i am little bit confused and not able to select the better one Department for myself the VAS or Core network.
i will be very thankful for informing me which one is better on the base of demand , salary , facilities and scope in market.
i am now trainee in ZTE VAS department.
so what i do remain here or go to core network department ?
i am waiting sir for reply ......
Regards
Bilal khan