Q. Can anyone tell me which paintball sniper rifle is the best?

Well Chris that's a good question.  The answer depends on several factors... what you want your sniper to look like, what you want it to do and how much you're willing to spend.  Of course the sniper paintball markers that cost the most generally have the most 'stuff' stuck to them and will obviously be able to do more.  For example the T68 Gen6 Extreme Sniper comes with a Phantom Thunger grenade launcher but this one goes for around $900 - it's a top-end gun with many available options.  Since sniper paintball guns are basically different brand name paintball guns with sniper attachments, your decision should be based on which type of gun do you like to shoot the best..... Tippmann 98, Spyder, BT, Tippmann X7, Tippmann A5 and of course the T68.  Beyond this, it's a decision about how long you want your sniper barrel, what kind of barrel, what kind of buttstock you want, how powerful of a scope or any other things you can mount on it to make it more rad.   I personally like the way the Tipmann X7 sniper paintball guns look and shoot, but it's all up to you.  You can't ignore the realism of the T68 having the capability of using a magazine and/or hopper.  The Alpha Black sniper is also a great looking marker.  After you've decided on what type/brand of gun you want to make your sniper, here are a few things you must have to make sure your sniper paintball marker is the baddest-ass paintball war machine on the planet....
You definitely want your sniper paintball gun to have a flexi-air buttstock; this will re-route your gun's air so you can put your CO2/hpa inside the buttstock.  There is also a little valve you can buy (called a 90 degree One Way Valve Adaptor) that will also allow you to switch right to a larger tank as soon as your gun's tank is empty.  I would also outfit my sniper with a 45 degree Swivel Bipod; this way you can turn your paintball gun and not have to pick up your bipod to point at a different target.  As a sniper, I like the one shot, one kill idea, but I would still equip your sniper paintball marker with an electronic trigger just in case your target starts to get to close or there's many targets close together.  A good scope to use is any of the Red Dot Sights/Scopes or a 3-9X40 Rubber Armor scope will do the trick.  I would recommend the new Rubber Armored Mark III Tactical with Laser; this way you will have a great scope + a laser already mounted to it, it also has a quick release mount.  Finally, just make sure you use a tactical rifled barrel; these are the latest in tactical paintball gun barrels.... a good one is the Flute Sniper Barrel.  You can find all of these sniper accessories on our site as well as many sniper paintball markers that already comes with everything we've mentioned.