Tough question. I'm probably going to have to go with Manakete. Panne is always one of my strongest units, so I always reclass her as soon as I can, and I've never actually used her son properly, so I haven't had the experience of using Taguel's properly. Olivia wass close second, her ability to allow my units to move again comes in handy during the early game, but becomes pretty useless when most of the children inherit Galeforce from their mothers. So, the only other logical choice for me is Manakete. Even after reclassing Nowi, I always bring her back full circle to her original class, and she's always one of my most powerful units. Being able to attack from two spaces away as well as directly is an advantage that you simply can't frown at. Plus, dragon's are awesome.