Way before Velika was revealed as a Great Being, I thought he was a really cool character. His cryptic dialogue and otherworldly skill with technology caught my attention... but then he was sidelined in favour of new characters in 2007. Apart from him though, I'd say... Johmak. Nice powers and the potential for an interesting backstory, but alas she was also buried under even more characters. Just one of the downsides of populating a universe, I guess.