BN Zero looks cool. he doesnt have nearly enough screen time to develop a personality, but in the Anime, he has very little of it anyway. being a very monotone speaker, with an unwavering voice. He is originally just an obedient soldier till he betrays his creator.
His heart is later (or before?) moved by Gutsman caring for him, when he mistakes Zero for a bystander that didnt escape quickly enough. He shows his usual self sacrificing personality in the anime as well, jumping in front of Megaman to block him from Zero One's Attack, and when Zero One is set to self destruct, Zero teleports him to the real world, and flies into his creator's ship, causing it to explode.
I can't comment on Transmission Zero, But there is similar. He was just a virus, but evolved, developing a soul, so he became pretty much like any other navi, with the exception that he is a virus. But he seems to be accepting of his fate when defeated. He also says "Youve come to defeat- Bust me, right?" (or something along those lines)