Evelyn-

"Better" is a relative word. If by "better" you mean "faster" then you must go the fiancee visa route, which will typically take less then 6 months while the marriage route will take 1-2 years, and the liklihood of you being issued a visa is far less. (For some reason the US looks more favorably on marriages conducted within its own borders).

We have a side newsgroup of about 15 Americans married to Dominicans or going through the fiancee visa process. I can send you more info on that if you are interested. Send me an email at gstern@email.com.