Unless you are playing Mil-tac, the best guns for scenario play are "Tourney" markers. They are designed to be compact, efficient, easily maneuverable, lightweight, ergonomic and in general just better than "Scenario" type guns for the purpose. There are many, many options depending on your budget, but in my opinion an electro marker from the likes of PE, DYE, Empire, etc. are what you should be looking at.