1. gMaps - essentially google maps for WP7
2. xmaps - offline maps, tracking and excellent replay of the tracked route
3. bingle maps - offers both bing and google maps
4. offline maps - as name suggests offers offline maps
5. bing maps - not functional in India at the moment
Depends, You talking gps powered road map apps? Turn by turn nav apps, or real, no bs GPS apps?
For turn by turn, I don't know. I don't use them.
For road maps, I prefer Gmaps to TA maps as a Google Maps interface. Otherwise, I just use the included Bing Maps. It's not bad.
Now, if your talking straight GPS apps,
- GPS Utilitity
Straight GPS info and conversions. Read outs and conversions for lat/long in deg/min/sec, decimal degrees, UTM, MGRS, plus allows custom map datum. Also reads accuracy, current speed, and altitude. Has a start/end feature for off map trips. Not the cleanest interface, but it works off network and works well to get coordinates in the three most relevant coord systems. Best for on the hoof stuff.
Simpler than GPS Utility and offers less info, but it is a nice, clean interface for showing lat/long (deg/min/sec or decimal), altitude, speed, heading and accuracy. Good for boat/desert type navigation. Only reason I keep it in addition to GPS Utility is for the heading readout and cleaner interface. Good for car/boat stuff. Works off network.
- Location Marker
A nifty app. Allows you to save locations and give them names and link pictures to the location. Pics taken from within app, so if you want to take multiple angles or vectors or what not. shows locations and current distance to them and interfaces with Google Maps, Bing Maps, and "Open Street Map." Allows for units in M, KM, ft, yds, and Mi. Coordinates in decimal degrees, Deg/min/sec, UTM, and MGRS. Only works when on network though.
Another nifty one is "Car Locator" which gives you a kinda corny green 1970's radar screen look and lets you guide yourself to where you parked your car. Rarely used, but kinda nice when you park in something like a stadium parking lot and can't remember where the heck your car is.