poker trackers

[steeveg01]

i like to play a lot of $1 to $10 tournaments, i am thinking of getting some sort of poker tracker, when your playing in a tournament you play against a lot of players who could be anything, a decent player who is dropping down a level or a maniac who keeps getting knocked out in every game he plays, are the trackers good enough to help me,ive heard they can influance you into making bad calls, but if i know the poker history of a player as soon as he is transferd to my table i would know how i stand,also some of these trackers are free with a sign up to certain sites, some you have to buy, any advice please which trackers to get and which to steer clear of