ROTFLMAO!!!!!
AM or FM has absolutely no bearing on how the signal "bounces" around.
It is the rf frequency you are operating at, the amount of power you are radiating, and atmospheric conditions that predominately determine propogation characteristics.
Personally I prefer FM operations because of the "capture" effect of FM discriminator circuits in rejecting adjacent channel interference. AM operations can get pretty tight on channel bandwidth, especially running ACSSB mode. Of course, nowadays with phase deviation narrow band digital and spread spectrum predominating the airwaves, coupled with the saturation of improved cell sites and low orbit satellite cell systems, it won't be long before all of our two way comms are full digital conversion, wristband sized bluetooth transeivers using hundreds of channels.
The days of discreet two way point to point comms is almost over.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)