I prefer the indexed/ratchet lever handle over the t-handle because:
I can get an extra 1/2 or whole turn or maybe 2 or even 3 in tight clamping situations
The lever is longer than the t-handle, providing a mechanical advantage; I can crank that sucker down *tight*. four fingers and an opposing digit yields much more torque-power than a thumb and the index and middle finger can.
I can swing the arm out of the way once properly clamped. I've had issues in the past where the position of the lever snagged coats/purses and/or stuck out in walkways causing a trip hazard.
In reserved seating situations with an extension pole clamped to an arm rest I've been shut down because the patron next to me bitched about the handle poking them in the ribs (and rightfully so). With the indexed handle, I can swing the handle parallel to the arm rest or at least where it pokes my thigh or ribcage not theirs.