In some ways I like the last one, and I agree it's the most interesting of the 4. The leaves being lighter than the sky they're lit by is disconcerting though. I think our eyes understand the idea that an object can't be brighter than the light source that it is reflecting. These trees, especially around the edges, almost look like some sort of chemical process is going on inside them that make them glow in comparison to the drastically dark sky. As Lew pointed out, there is a lot of fringing in #4 as well. ie there are white lines that delineate where the processing on the sky stopped and started. It's a dead give away of heavy processing.
Heavy processing isn't bad in and of itself, but when the eye can clearly see the artifacts of it, it usually degrades the image.
I have no issue with the general look of the last image, but if you're going to process that much, it is a VERY painstaking process to get it to look just right. If you half way do it, the viewer quickly picks up on the 'tricks' and a good but heavily processed image has to be like a great magic trick, obvious in some sense that magic has gone on, but not obvious as to how it was actually done.
