honestly, I suggest that you do what you want to do. Do you play any first person shooter games? If so, which do you prefer on those games? Do you do any shooting for real? If so, do you prefer to shoot close targets or long range targets? I mean honestly... It's up to you. If you're still on the fence... you may consider something like the SAMR/DMR that the US Army/US Marines are using now. It's a standard issue assault rifle with optics attached and a little fine tuning. Gives them the ability to have an "Advanced/Designated Marksman" within each rifle squad. Also, You may check out my WIP thread and look at the carbine my character has, I'm considering mass producing them for distribution.
Kal