Changing Unifi DIR-615 router, Need some help here

I have gone through the forum for the past few days and I found out that TP-link offer cheap and good product~
I need a router with QoS function cause my sis always uses PPS and it's killing me when I'm gaming!!!!
The signal is weak in my room also tho.
My budget will be around rm150.
Any advice on which model is the best for me?
And 1 more question does QoS works if I'm using wireless connection? Cause all of us are using wireless to connect.
Thanks in advance!