If you fancy yourself an anime fan in the least you should at least watch DYRL and Macross Plus. SDF Macross can be a bit intimidating at 36 episodes, but it is so fucking fantastic. Shoji Kawamori cleverly hid the best love story ever animed in a robot-punch-em-up show.
Zero is definitely worth it too, especially if you want to get the most out of Frontier. It's been one big nostalgia trip for me, but I'm borderline oldfag at 25.