In unlimited framerate mode the cpu sends all orders to the gpu as soon as all calculations are done. This can produce side effects like tearing and your game is dependent on a fast pc with a fast graphics card.
While you may experience more responsiveness of your game, another player with lower specs will not. So every player will experience something else. You could of course define some minimum system requirements (preferably the ones of your developer system) to make sure, no one is disadvanteged.
In v-synced mode the cpu does its calculations and then waits for the vertical refresh of the monitor before sending the orders. This way no side effects will occur and all players will experience the same game speed/responsiveness down to the weakest system that is able to produce the v-synced fps (e.g. 60 fps on most LED/LCD monitors). Only when the system isn't able to keep up with v-synced, it will suffer disadvantages of slower responsiveness. That's what unlimited framerate is good for. To see how much headroom there is. It gives you a measurement of how much slower a pc might be to still be able to play the same way as you experienced it in v-synced mode.
Overall: If you don't care about the disadvantages and the side effects for slower PCs, you might as well use the unlimited framerate mode.