All accents are fine, it only depends on your preferences. Anyway, to start learning a language you have to concentrate on the educated version of that language, it could be Spanish from Spain, Mexican, or Dominican Spanish depending on which of those countries you are planning to visit. But, as you well said, as a beginner you shouldn´t worry to much about that.

I think Dominican Spanish is very fast and many words are merged together. I've talked to Spanish speakers in other countries who have trouble understanding Dominican Spanish. Places like Peru tend to have a more neutral accent, so it is more easily understood across all Spanish-speaking countries.

I absolutely love this!!!!!!!!!! My personal opinion is that I just don't like the Dominican accent. That is to say, there are specific phonological features that I find very unattractive, but it's still an important accent in its own right. I think you should choose to imitate the accent you like best. The Spanish accent, spoken in the Northern and central part of Spain is considered more standard Spanish if you care about these things. I'm starting to pick up the CHilean accent, so clearly I don't. If you can understand the Dominican accent, it will really help your comprehension. I've traveled to countries with more difficult accents to grasp just to improve my listening skills. I hope this answers your question. Good luck!