This really depends on the objective. For instance if you would like to create a link to navigate in Waze or show a location in streetview, you will have to provide decimal degrees (geographic coordinates WGS 1984, Lat/lon), but for having easy access to properties of area and length it could be better to use projected coordinates (X/Y) or for instance for doing distance calculations with raster data, you would also use projected data (X/Y).
What kind of data do you have and do you want to do with it?
Thanks Xander for your prompt response.
I have do reverse geocode of points. I provide mapping services for
location of utility problem or road repair.
So I have give the crew the exact address and location to navigate/route.
Let me know if you have any thoughts on that.
I have address data. I want to select a point on a map and be able generate an address. (reverse geocode)
But sometime I just want to find a route to the point selected on the map.
That captures the data in x/y and Lat/Lon format. Now I need to find out which one I should and why.
So you have both coordinates and need to define which one is best to send out to the field crew so they know exactly where to go... The best option depends on the mechanism that you want use.
The ArcGIS platform allows you to use Workforce for ArcGIS | Mobile App Solution for Field Workforce Coordination and create assignments and assign those to the different field crews. They will receive a notification of the work order and the location and optionally be able to use Navigator for ArcGIS | Advanced Workforce Navigation & Routing to navigate to the location and register the work the carry out using Create Smart Surveys & Forms for Data Collection | Survey123 for ArcGIS or Mobile Data Collection App | Collector for ArcGIS - Easily Capture Field Data . You can monitor the process in real-time using Operations Dashboard for ArcGIS | Real-Time Data Visualization & Analytics .
This would depend on:
Your needs - do you need to portray accurate area or distance / direction.
Your other data - are your other data layers in x/y coords? it is good practice to try keeping all layers in 1 coord sys
Your extents - continental scale is inappropriate for UTM/State Plane, as you will span multiple zones and create distortion.
That said, We work within state plane zones, or UTM zones most frequently, but I am focused on continental US and specific sites / areas within it, and our analyses and model output / input are in feet or meters, and therefore put us into x,y coords and not geographic lat/long.
I am sure that the user community will have additional input to this open ended question....
We use both lat/long and XY coordinates as well as other locating systems quite a bit here in Manitoba. We dispatch ambulances for roughly 640,000 sq km with about 94,000 km of roads. We dispatch ground and air resources into a variety of areas requiring different wayfinding tools. The system we use depends on who the final user is of the data (pilots prefer latitude and longitude), ground ambulance prefer civic, street or STR addressing and if they need to be away from the road network we can use UTM coordinates (in whatever datum their maps or gps are set to).
Interestingly because we interact and train many folks whom map use is of varying degrees of importance we have streamlined the teaching about any coordinate system to essentially depicting them all as an XY system even though that is stretching it a bit for lat/long and of course does not work at all for STR.