Booggie
I think DC has more potential & will be better considering his current level of strength . He can not only interact with the supernatural world but also the sci-fi & alien civilizations . Maybe he can find an even better romantic partner there since I feel like he doesn't really have a romantic relationship with anybody in the TVD world .
When transferring worlds he should be able to get a power up from said world. For example if he goes to dc he should be able to activate a meta gene or something like that. Each world could be a hard reset but he keeps the powers he collects in each lifetime. If you do go for the dc route then he should be reborn on appokolyps. Dude needs some sort of buff to contest with higher level worlds. Just spitballing here.