I'm gana throw in my idea of the lone wolf, since i sometimes like to play the part. Lone wolves go out and do their own objectives solo, with out the relyance on a team. They tend to not expect any help from their team, and are frequently more considered useless, dispite their distinct acomplishments. A few people already mentioned the true fact, the lone wolf tends to rack up the most kills. I played the recon in BF2142, and used the cloaking system and the carbine with a stupid level of efficiency, i'm talking 20-1 kill-death ratio. (did you know that it works better outside in the light then in the dark? the shader it uses is more visible against a dark background as it would create a very noticable ghosty outline).
Anyway, the reason i was so effective is because while working alone, you can skim the edges of hotspots, and go places most people dont look for. Others just got in my way really.
Of all of these, i will probably be adapting the baiter, though its not exactly accurate. I'll never sacrafice any one to get MY kills, i need my guys to pull them into a position where i'll be waiting for them. Personally, its the most satisfying tactic i've used. My play style usually ends up with getting people killed even if i didnt do it. In WoW i would sap enemy rogues out of stealth and watch as 3-4 guys jumped on them, and in bf2142, i'd put some pain down on them, then lure them into a friendly ap mine. My kill? no but whatever theyre dead right?
Regaurdless, in brink, i'll be picking up the most deadly package i can get ahold of. I just like killin people i guess :shifty:
If you really want to be a sniper, you might try agile soldier or agile operative. Soldier for extra ammo and cool grenades that you'll be able to use to tactical effect, or operative for the ability to spot enemy operatives in disguise, and hack enemy comms after you get kills.
Unfortunately for you and everyone else who loves high K:D ratios, Splash Damage doesn't want there to be long-range sniping in Brink, and the sniper rifle is not going to do instant kill damage. Sniper rifles will be considered "light" weapons, which means agile body types can carry them as their primary weapon, and medium and heavy body types can use them as their secondary. It also means they won't be very powerful, but by the sound of it you're okay with having to rely on your team somewhat to get you kills, or to finish off your targets.
You should know, though, that Brink rewards players a lot more for doing things besides killing the enemy. It's objective-based, and ultimately the objectives are there to drive the combat, but that still means that if all you do is shoot at people, you'll be considered pretty useless by your team unless you're very good at it and you do it in the right places. Know that you get more XP for shooting the enemy if they're near an objective.
If you want to balance combat with objective focus, you could be an agile medic or an agile soldier: climb up to rooftops and snipe, and when your teammates need ammo or medical attention, swoop down to the rescue, and then resume sniping.