In most cases, people's own sexual orientation will dictate their choice. For example, a heterosexual man will choose to date two women because he often fantasizes about being able to have sex with two or more women at the same time. Whereas a gay male would not do this, he would probably invite 2 other men to a threesome simply because he doesn't like women. And if this is a bisexual male, then he is more than willing to have a threesome with a male and a female, because it will satisfy all his needs at once.
So that being said, before you make your choice, you better figure out exactly what you want. If you are still single now, then you are totally free to make your decision as per your preference as you will not be restricted by any restrictions. But if you're in a relationship now, or even married, then you have to take into account not only your own needs, but the needs of the other half as well. Because it's almost impossible for you to skip your other half directly and go into a 3some alone, doing so will only have serious, unwanted consequences. So, you should talk it over between yourselves and find a way that is acceptable to both of you, rather than one of you doing what you don't want to do in order to please the other.
Also, when you are looking for a partner, you should ask them if they have thought about it, as not everyone is clear about the need to do so. You can also exclude those with a different orientation than you, so you can avoid wasting time on them and target those potential users faster. On those apps and websites, you can easily search for and get in touch with a large number of threesome lovers, and if you're lucky enough, you can totally schedule your own threesome hookups in no time at all.