In response to an earlier post, Robotech isn't just Macross but is rather a collaboration and reinvention (and in some views a bastardization) of Super Dimensional Fortress Macross, Super Dimensional Cavalry Southern Cross and Genesis Climber Mospeada.
Also, Voltron is a collaboration and reinvention (and definitely a castration) of Hundred Beast King Golion and Armored Squadron Dairugger-XV.
In all fairness, if American animation isn't being considered anime (which is really an English word anyway), then American animation collaboration projects shouldn't be considered anime either.
In any case, off the top of my head, my favorite anime series and/or sagas would have to be
1. Macross (SDF: Macross through Macross Zero)
2. Sentou Yousei Yukikaze
3. Yoroiden Samurai Troopers (translated and released as Ronin Warriors stateside, but unfortunately without the OVAs)