You played what in
40k? Necrons and
BA? Yeesh, both of those factions are pretty far from those two
40k armies...
Circle Orboros is a fiddly, movement intensive army who uses positioning and deep strikes to win. It is a scalpel in a sword fight.
Legion of Everblight is a Beast heavy faction (in that there is more beast support than infantry support) that is also very good at manuver, but is much better than Circle at ignoring the effects of terrain and get some egregiously long alpha strikes. They are very fast, very aggressive, and fairly weak on defenses (with notable exceptions,) making them a glass cannon army. LoE is a dagger in the back from the shadows to a swordfight.
If you played Dark Eldar in
40k then LoE is a good transition in terms of playstyle and even look. Circle takes a bit more getting used to, but is capable of no less impressive feats of carnage, it just requires more planning and patience than LoE does.
IMO Circle is the most finesse intensive army in
WM/H, and much like Tau in
40k (or
DE for that matter) is not an army I would recommend beginning with. But, given the number of LoE players in the game, I guess I'd go with the lesser of two evils.

Go Circle.