Double A-Arm:  The best, when it's done correctly.  (Some manufacturers use light-weight arms, and they don't hold up well.)  The Twister Hammerhead series karts are a good example of this technology "done right."  Make sure you buy a reputable brand whose parts are readily available.  The suspension is one of the most unique sections of a go-kart, and if replacement parts aren't available, you may have to "retire" your kart much too early.

SWING ARM:  Popular, but most manufacturers "cut corners."  This system utilizes two swing arms.  Each arm pivots on a bolt on the frame of the kart, the other end goes up and down and holds the wheel.  A spring (usually not a real shock absorber) limits the action.  Think of this as a bird flapping it's wings, with shocks on the wings.  This looks cool, but has two major problems.  First, as the arms swing up and down, the angle (camber) of your tire changes.  This can make steering the kart very difficult (it may jerk from side to side) as the arms move constantly while the kart is moving.  Second, as the arms pivot on the bolt, it wears on the bolt and the swing arm.  Unless manufactured with a bushing and grease fitting, this wear causes the arm to start moving forward and backward, allowing the swing arm to hit the frame.  Major repairs can follow.  Depending on the strength of the materials, this design may be problematic, and very expensive to repair or replace.   Demand bushings with grease fittings on the pivot point.

The light-weight version of the swing arm is what you find most often at warehouse and chain stores.  The heavy-weight version (supplied with grease fittings) will alleviate many of the problems, but it's often difficult for the average consumer to discern between them (a real shock absorber is preferred, not just a spring designed to look like one).

“4-LINK”:   This type is a spring (not shock absorber) suspension, but it has multiple pivot points to avoid the camber problem of the "swing arm" style, somewhat like a dual "A-arm."  The 4-link insures surefooted handling, precise steering, and better tire life.  This system is no longer being used, to our knowledge.