I'd also recommend going for light, gotta utilize that damn 100% if you happen to have it. Well.. Sol or Tsukuyomi. Great question. I'd say Tsuku nevertheless, but that's probably just my veteran bias. Sooooo.. let your dick do the thinking.
I think it's a lot easier to start out with Sol than with Tsuku, considering how strong heals are in the beginning. Not sure if in days of relic weapons, Tsuku is still as essential and irreplacable as she was in the past.