For a single, particularly one with no prop lever, I think plungers work better
I agree. I find that plunger throttles are much more comfortable to operate and more intuitive than the awkward lever affair found in later-version PA28s, especially when making power changes on the approach. The oversized handle thing looks as though it should be operated using the palm of the hand however small movements, as necessitated by the short travel of the mechanism, are difficult to make if the throttle is held in this way.
I'd say that the C172 is a better trainer than the PA28 even though the latter is generally a better aeroplane. PA28s breed co-ordination laziness thanks to the aileron-rudder interconnect and the Warrior/Archer is too easy to land to be a good trainer in my opinion.