Complete is always preferred BUT.. it depends on the scarcity of the missing piece and the purpose of buying the figure.
I like complete figures in my collection and since my TFs are mostly post-Armada buying them complete is not too hard. Once you start talking about pre-Beast Wars i think you have to consider the scale of price vs quality vs completeness.
If i wanted to kitbash a figure accessories are usually not required.
If i wanted a quick look at an interesting dirt cheap figure i can forgo some accessories too.
^All of this has a caveat that i know about the missing bits and do not think i have gotten shafted.
PS. I am looking for a Ramjet minicon that comes partnered with Armada Tidalwave.