I’m a fan of asymmetrical forms, closer to triangle than teardrop, though in my opinion closer to the natural curve of a breast (at least on my particular figure). A couple words in general on breast form selection:
Measure twice, cut once. This is particularly important if you’re buying online. What I do is take a cloth measuring tape (and if you don’t have one get one, girl you’re gonna need it!) and mock it out on my chest based on the listed dimensions. If dimensions aren’t given, I’d just hard pass in general.
Second word of advice is resist the temptation to cheap out. And this coming from someone who has to seriously budget for all her girl-stuff. The old adage is true here for the most part: you get what you pay for. Not that you should immediately go for the high-end forms, particularly if you’re unsure about sizing or your commitment, but avoid the bargain-barrel stuff.
Hope this helps! 😉