I don't know if there's a definitive answer. There are things that make each one harder and easier. On one hand, being bi can be easier because you can sometimes pass as straight. If you're a woman and you marry a man or vice versa, you will greatly reduce the amount of homophobia you will face. Of course, you can still face homophobia if you are out as bi even when you are in a straight relationship, but it is safer and, if necessary, you can completely hide the fact that you are bi. On the other hand, gay people don't face biphobia. Between the stigma that comes with being bi (the idea that you're just pretending or you're promiscuous or whatever other stereotypes exist) and the violence faced (bi women experience the highest rates of rape and domestic violence compared to straight and gay women; bi men experience the highest rates of sexual violence compared to straight and gay men), biphobia can be really harmful. So I really don't think one is easier than the other.
