TNC Modem

Considerations are different because your country and your area are different.

Mostly depend on the geography of the land and the number of available stations.

If you have a hight density of mobile stations is different than just few fixed stations.
You better want to talk with same local amateur radio to discover your setup. He may also provide you good tips. My considerations are based on the North of Italy, but I also have experience of the Bay Area (California), feel free to contact me !

Just know that APRS in Europe is on 144.800 MHz and in USA is mostly on 144.390 MHz