I do think the language that you watch an anime in first hugely impacts your opinion on any others that you watch afterwards.
I've always been an advocate of the original Japanese dubs, though, because I feel that the Japanese VA's put way more effort into their voices than the Americans do. Then again, the target audiences for the American and Japanese shows vary widely as well, with anime in Japan being watched by anyone aged 10 to over 30 (or something) while the American shows target almost exclusively 10 to 15 year olds or thereabouts. As a consequence the younger generation doesn't seem to care much about the voices. I know I didn't when I was younger.
Regardless, it is a matter of personal taste in the end. I watch what makes me happy and other people watch what makes them happy. ^^ I do think American VA's have come a long way recently, though, and they've started cutting the shows a lot less (uncut DVDs are awesome), so maybe there's more potential for them to grow, in my eyes.
There are some animes where I prefer the English voices. Tenchi Muyo, for a start, and DBZ (what the hell is with Goku's Japanese voice? O.o). Also, the Lost Odyssey game has better American voices, imo. I mean, the Japanese gave a female character a male VA! O_o
But, yeah, my two cents. XD