Buying new ADSL2+ Router on Airtel wifi broadband connection?

Guys, I need to replace my wifi modem given to me by airtel at time of installation..I mostly use wifi.
Requirement is long range and stable connection..
Preferred brands: ASUS or TP-Link
my old modem is BEETEL 450TC1 ADSL2+ ROUTER..

Budget is 1.5k-2k.
Thanks!!

PS- Buying it tom so reply soon plz