RST is "better"
There are so many human readable markup languages now. Each one is tuned to the specific purposes of the author, but they all seem to have at least one or two issues.
It seems the primary benefit of txt2tags is the lightweight generator tool, but it still needs a two step process for PDF, my most common output format.
I hate the txt2tags mark up, it seems so much like code and has too much repetition. Like """ and //. I also hate when you have to use specific coded strings to make something happen. I want it to look as much like natural language as possible.
RST is better for me (but still has some glitches). txt2tags is more like a conglomeration of several wiki markups. I don't like it.