If you're planning to do all your diving on vacation for now, consider renting as much as possible until you know what you want. Take good notes in your logbook about what brands you used and how you liked them.
When diving locally, owning is freedom and renting is a hassle; you have to make two trips to the dive shop immediately before and after every dive day. For me that means sitting in Friday evening rush hour traffic in LA, which has a suck index almost as high as diving's fun index. The rental costs add up, and they especially sting when you end up not even getting to dive because of weather or illness.
But when you dive on vacation, renting can feel like freedom and owning can be a hassle. My suitcase with just my dive gear was almost exactly 50 pounds on the way out, and it was over 50 on the way back from my recent trip because my wetsuit didn't dry. I had to carry this wet smelly thing in a bag to avoid the $100 overweight luggage surcharge. And I didn't even have my reg or camera in my suitcase; I carried those on to protect them, leaving me very little room for non-diving stuff. Since it was a liveaboard, I didn't begrudge all the baggage; I wanted my special gear that I spent months picking out for a vacation that was basically just eat, sleep, and dive. But honestly, the two trips I did before I owned much more than a mask were so convenient. One of them I managed with just a backpack.
For now, get a mask that doesn't touch your face anywhere but the skirt and stays put without a strap when you inhale slightly through your nose. Get a snorkel, fins and booties if you have to for your course; I really wish more shops would allow you to rent those. (OK, a snorkel should be cheap enough to buy, wear until you're certified, and then do with what you will. I'm not a fan, personally; mine stays in my dive bag, but opinions differ. I don't think very many people think the choice of snorkel type or brand is critical.) And maybe think about a computer, just because it's nice to get familiar with where all the numbers are on the face. There are several perfectly fine entry-level computers for around $200, and it's also a perfectly fine thing to buy used, which can cut the price in half.
Start buying when you start feeling like not owning is holding you back. Then spend some time here and talking to local divers to figure out what you want.