Hi,

For Budget & Recommended is this one:
ASUS 300Mbps Wireless-N Router (RT-N14UHP): RM320

Anything regarding WiFi signal will have No Actual Answer. That is because:

- You can have better coverage with lower security setting. A open wifi or non-security setting has better coverage than WEP, WPA, WPA2. WEP has better coverage than WPA... and so on.

- Nobody knows the best position on the location to place your router without onsite testing. To prevent dead spot, interference and so on.

- Nobody knows the surrounding users on your neighbourhood that uses which WiFi Channel without onsite testing. A same channel WiFi setting with your surrounding neighbourhood with affect the coverage & speed of your WiFi.

- Nobody knows is there any 2.4GHz interference equipment on the surrounding areas like wireless video/audio transmitter where it affect the operation of 2.4GHz WiFi signal. Also is there any fire proof or sound proof wall or door like the karaoke room in your house that weaken the signal. That is why a Dual-Band Router with 2.4GHz & 5GHz are better.

All problems has it's own solutions including using Homeplug, Access Point, Repeater, CPE etc. to solve the problems that is not only changing the router.