OVPN vs SSTP

Looking for the best and most reliable way to create a tunnel from a remote mikrotik (behind unknown firewalls) to the primary MikroTik on our network. We figure that SSL is probably the best protocol to use and is rarely blocked on most of the networks that we work with. After looking over all of the information that I can find, it appears that the 2 options for Site to Site SSL VPN are OVPN and SSTP.

Question, is there a good reason to pick one over the other? Cannot really find the major benefit of one over the other right now. I lean toward SSTP but could not really make a case for it over OVPN.

Thanks!