You didn't keep running because lag would have your head before long. I swear I can put 5 bullets into someone, not seen a single hit on either me or my enemy and they're left with maybe 75% health. BS
Well, the best thing to do is probably to just lay out what all of them do, and see which one fits your play style best. From the wiki:
Marathon doubles the player's sprint duration. Its Pro version gives the player unlimited sprint duration.
Ninja reduces all player noise by 75%. Its pro version completely silences the player and doubles the volume of enemy sounds. Teammates without Ninja will be heard normally by the player.
Tactical Mask renders the player immune to the effects of Nova Gas. Its Pro version reduces the effects of Flashbangs and Concussion Grenades on the player by 90%. This is to say that if hit by a Flashbang, the player's vision will dim for a second before returning to normal. If hit by a Concussion Grenade, the player's vision will blur as if stunned, but movement and turning speed will be unaffected. This lasts for about two seconds before the player's vision returned to normal. It also reveals the general direction of any enemies that are hit with the player's Flashbangs or Concussion Grenades via a small yellow directional indicator near the cross-hair. If multiple enemies are stunned or blinded by the player's tactical grenades, multiple arrows will show up on his cross-hair.
Second Chance lets you live for ten seconds longer after you've died. You'll be left with one HP, so any damage whatsoever will kill you. You'll pull out a pistol (and if you had a pistol equipped it will be that one with the exception of any pistols with Dual Wield and the Full-Auto attachment on the CZ75) when you fall and can still fire. Pro version lets you live for 30 seconds and be revived by teammates. If killed by a headshot, knife, shotgun blast, or most explosions, the player will bypass Second Chance completely and die immediately. --One note on this from me: Many players (myself included) hate to see this perk used because when coupled with lag it becomes overpowered, allowing the downed player more than enough time to kill his attacker while he remains invulnerable.
Hacker makes all enemy equipment, Sentry Guns, and SAM Turrets glow bright red. The glow is visible through all surfaces and from any distance. Its Pro version allows the user to booby trap enemy Care Packages, turn enemy killstreaks (i.e. Sentry Gun and SAM Turret) and equipment friendly, and remain undetected by enemy Motion Sensors. It takes three seconds to hack enemy equipment/killstreaks. When hacking an enemy Care Package the player will capture the package normally; in addition, a decoy package will appear in its place. The decoy will appear as a random killstreak reward to the enemy, and as soon as a player attempts to capture the booby trapped care package it will detonate, killing the person who set it off and any other nearby enemies. When hacked, the care package will change color from red to black from the hacker's team's perspective.
For me, Hacker's letting me see enemy claymores alone saves tons of time and deaths, while allowing me to destroy them from a distance since I also use Hardened, thereby saving allies from them, as well as getting the occasional kill when an enemy was in front of them. The stealing enemy equipment, booby traps, and invisibility to motion sensors is icing on the cake.
the hacker or marathon seem to be the most helpfully; ill proably try the hacker because seeing claymores seem like a deff plus ability and can save you alot. thanks cobalt