That's what I find fascinating about them. My reactions are visceral, not intellectual, and they vary from time to time. That keeps them interesting for me. They are engaging but elusive and as a viewer I find myself an active participant rather than a passive viewer.
At the moment, #4 and #1 appeal to me the most, and #2 the least. But that probably means I need to spend more time with #2.
Keep 'em coming, please!
Eric