I may have missed something -- it's late! -- but do any of them enable you to find out if Real People are looking at an RSS feed, as opposed to it simply existing and being indexed? I don't mean anything as precise as a hit-count, but something that would indicate whether someone has my LJ RSS on some sort of aggregator.
[Assume I am completely ignorant of RSS stuff, and you won't go far wrong. Splendid in principle, time-consuming and haven't-got-round-to-it in practice!]