I've just started Trigun, but I didn't think the acting in the dub was that bad. I judge dubs solely on acting, since I am not a rabid purist (the story does not lie in which language it is spoken; the story lies in <i>the story</i>, which is a combination of script, acting, and visuals), nor am I married to any one sound, the "But ___ doesn't sound like that!!!!!" wail.
Now, casting is a concern - I didn't like the casting of Miki in SKU, since he sounded far too old, for instance - but I just don't understand the fetishization of the original audio track. *shrugs*
Watch whatever you want to watch. Who the hell cares what anyone else likes? It's a matter of taste. There is no one "better" or "worse" across the board.
And as already mentioned, DVDs usually have both. (though my copy of Trigun won't play both tracks on all the episodes; that's another matter.

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