Personally, OTV and VXLAN have some overlap in functionality, But they are partially targeted at solving different problems. While both protocols address L2 connectivity across L3 networks.
VXLAN also addresses the exhaustion of the VLAN address space in larger networks (especially service provider networks). - it also has the added benefit of supporting a 24 bit VXLAN network identifier (VNID) so where a VLAN can support 4K "ids" VXLAN can support about 6 million VXLAN segments.
This is an issue that OTV does not try to address that issue.
Again It all depends how we want to deploy where, use cases are different.
Make Sense ?
BB
