It is preposterous to compare character development area betweeen Plus and Zero, since Plus had finished and Zero is still going on.
Iow, since Zero is still not finished, character development is in progress in Macross Zero.
Fwiw, here are the major character-developments in Zero so far, imho:
[*] Shin:
-- skills: from hothead ace F14-pilot to a grunting second-rate Valkyrie-pilot that's still adjusting to Zero's new multi-role combat capabilities and new combat tactics.
-- emotions: from typical arrogant angsty loner to a more worldly and sociable dude that realizes and acknowledges the inherent conflict between old-world culture (mayan superstitions, myths, lore and laws) and new-world culture (technology and medical benefits) and strives to bridge the two for Mayan sake. Still sorting out his feelings with Sara and at the same time realizing Mao's rather-inappropriate advances.
[*] Sara
-- deadset against technology and outsiders. Slowly accepting Shin as a man, but still has reservations and hostilities about everything that is not Mayan, including her mixed emotions with Shin.
[*] Mao
-- Established opposite viewpoint against Sara's Mayan-only viewpoint. Developed first crush on Shin and realized her sister Sara is a rival. Sibling-rivalry.