I'm working on an application in Flex will utilize mapping features. I have experience with the Google Maps API in Flex, but it seems sort of limited to me (as compared to other APIs and the Javascript API). In particular, I'm interested in developing some clustering (grouping places together to prevent too many points from being on the map at once, slowing rendering). I'm wondering if anyone has any recommendations on which API to use/look into, and perhaps which APIs have features unique to them. I think visually some of the other providers have "nicer looking" maps as well. What I'm checking now:
Google Maps API
Have a lot of familiarity, but might be missing some key features.
Yahoo Maps API
Don't know a lot about it. Seems to handle a lot of markers very well. Looks really nice visually. 50K requests per day for free is less than google.
ArcGIS SAMPLES
I've had my eye on this for awhile. Seems really robust. Great samples index. Also seems to autoscale markers based on the zoom depth. They also seems to have a lot of data-based maps you can access.
MapQuest API
Looks to have great docs and features. Noteable are the "decluttering" and I think it has clustering.
Going through this awesome list right now, but I'd love to know if any of you Flex (or other lang!) devs have any experience with mapping and would like to give some advice.