I would have easily said Garmin but having checked AVT first before saying anything, I might be tempted to say AVT seems to be a better choice for GPS navigation within the Philippines since the map provider is ACCU-MAP which is a Philippine based digital cartography company.

Downside, the AVT A-800 unit is kinda pricey at SRP P18,500. Garmin GPS units are available starting at P9,500 and up with Metro Manila map already loaded.

Accu-map official forum: (map provider for AVT)
http://www.accu-map.com/forum/index.php

Accu-map offical website:
http://www.accu-map.com/index.html