The most popular type of airsoft sniper rifles seems to be the type 96 model, which has a grip similar to a pistol. Most of the cheap airsoft sniper rifles are not type 96 guns. Also, it would seem that for the most part most people want to go with a black or a camo colored sniper rifle airsoft gun; perhaps this is because a black or camo colored rifle is perceived as being harder to see by other airsoft players? Lastly, there are some other fairly popular color variations for airsoft sniper rifles, most notably the OD Green, the desert camo, and the realistic looking wood color design.
Many of the high end airsoft sniper rifles come with a scope, bi-pod, and usually a sling as well. And if you want to upgrade the scope that comes with it, that is usually pretty easy, as most of the good airsoft sniper rifle guns have a real scope mount, much like a real sniper rifle does. This gives you a lot of flexibility when it comes to upgrading the scope. Some of the more expensive scopes that can be used have illuminated reticles, which usually run off of AA batteries.
As far as velocity, most of the good spring airsoft sniper rifles fall right about within the 450 to 480 FPS range(using 0.20g airsoft BBs), while the electric airsoft sniper rifles shoot at a slightly lower FPS. Spring powered airsoft sniper rifles are always single shot, and need to be cocked every time before being fired. This is what makes airsoft sniper rifles so similar to the REAL sniper rifles used by military & law enforcement agents!
The gas airsoft sniper rifle is also fairly popular, but unlike the spring airsoft sniper rifle, it is less realistic than traditional sniper rifles, due to the fact that it is semi-auto. Also, they need to use “green gas” to fire, which means that, unlike the spring powered airsoft sniper rifle, the amount of times that they can be fired is limited by how much gas is remaining. This is probably the main reason why most people prefer the bolt action (spring) airsoft sniper rifle. Another factor is that you can get a spring airsoft sniper rifle cheap - unlike the more expensive gas airsoft sniper rifle.
The 2 most popular manufacturers of airsoft sniper rifle guns are UTG and Cybergun. It is safe to say that our most popular airsoft sniper rifle is the UTG Shadow Ops Type 96 airsoft sniper rifle, followed by the Cybergun Mauser Pro Tactical Type 96 airsoft sniper rifle. The UTG Army Digital Shadow Ops (Camo) airsoft sniper rifle is also quite popular as well. Some of the other, less popular airsoft spring sniper rifle gun manufacturers are UHC, TSD, and Crosman. Also, surprisingly enough, the popular manufacturer, Echo 1, does not seem to even manufacture true airsoft sniper rifles for some reason. However, they do make a lot of high end airsoft m4, airsoft ak-47, and airsoft m16 rifles, which can be used as semi auto sniper rifles.