I have had the same sort of problem, Paulbot. With the recent shameless repaints and "versions" of characters (same character in different size classes) I have found it hard to get excited. The new Universe and part of the Animated line have done this for me, but I really miss the old days where Bumblebee was a Minibot and no other size, Optimus Prime was a larger toy and not remolded in every other size, and there was only one toy for each character.
Sure, it is my choice to buy the other sizes, and I could just choose to buy the one size or class of character that I think fits best, but we are often left with subsequent waves introducing better versions or more appropriate sizes (Leader Bulkhead, Movie Megatron).
I am really trying to find the magic again, in time for the Collectors interview!