Flash for macro

[ChrissyMarie]

I am calling for help because I seem to be in a total minefield. I have recently treated myself to the Sigma 150mm lens.
Having taken lots of insect pics in the summer dragonflies and butterflies, I want to take my insect photography to the next level but I know that I really need some extra light.
Most of my photography is done out in the field, crawling around woods and fields and I cannot see that changing, although recently I have quite enjoyed crawling around and snapping shrooms too
So I have been looking at ring flashes and flashguns and am totally confused. It seems that some people swear by the Sigma dedicated ring flash and others seem to berate it. However, if they berate it, I have been unable to find out what it is that they are using.
I really do not want a bulky setup for what I do, I already carry around quite a bit of equipment and space is at a premium, my camera is a Nikon.
Any suggestions anyone?