I've just recently got back into watching anime and my favorite of all time has got to be air gear. but the one i am about to finish is coming to rank up in second place, its called Soul Eater.
Soul Eater is similar to Air Gear with its mood and the style of anime that it is. However Soul Eater is much darker, and has a lot heavier element of reality and consequences. Soul Eater is a constant battle between good and evil, but even then the good characters can be rather ambiguous at times and it makes for an intense, thrilling, fun, and hopeful show :)
While Air Gear is not as dark it is still just as intense and thrilling. Air Gear has its theme placed much higher in the sky than down in death city. Both shows have enticing women characters whom always pop in and out of your mind in between long fights and grueling battles. Air gear is a little more happy and uplifting.
Anyways, After the long days work its nice to watch either of them. Until Next Time!