In terms of speed, they are comparable. The great benefit of WireGuard is simplicity on Linux compared to the configuration nightmare that is StrongSWAN, but implementing IPsec/IKEv2 on OpenBSD using OpenIKEd is roughly comparable if you use Let's Encrypt certificates.
You can get really inexpensive GL.inet GL-MT300N-V2 "mango" boxes (about $20) that will provide transparent WireGuard or OpenVPN encryption for a device that doesn't support VPNs out of the box (ahem, a Smart TV or streaming box, to bypass geo restrictions). They don't support IPsec.