Looked at simply, Trigun is set in a fantasy Wild West, with Insurance Brokers and cars. It is absolutely fantastic. The leading man, Vash, has a 60 billion dollar reward on his head. Vash is a number of things. Let me outline them:
Awesomely Cool
Awesomely Moronic
Awesomely Skilled With A Gun
Awesomely Overconfident With Women
Awesomely Perverted
Awesomely Mysterious
Awesomely Picked on
Awesomely Powerful and swift-He can dodge a speeding bullet.
And in general, Awesomely Awesome.
Vash is what makes this series so great. There are many other characters, many quite funny and deep, but Vash is the heart of the series. And Vash rules, so who's complaining?