I've been using Photoshop and Photomatix for awhile now along with Topaz Adjust. I also do a lot of reading here and many other places as well, about different software you can use to improve an image.
I got it down to 3 that I know of that look interesting:
1.) Nik Color Efex pro
2.) OnOne Phototools
3.) Onone Phototune.
Along with Lucisarts, but just too expensive for me.
I also agree that probably the best way to get good images is with getting my images good in the first place, especailly HDR, since lately my shots don't seem to be very good in the first place.
But that aside which one of these or any others you may think of would be most useful?
I also agree that ahving too many options is probably not good either, it may just put a strangle hold on too many things to try.
All three you list do different things but I believe all three have free trials so, try them and see what you like. Remember that the Onone software is accessed through the automate function and not the filter. This is off-putting to some.