Non-Completist for the most part. Whatever my interests, the collecting aspect needs to be anchored to something - for example I might buy every toy released with the names Starscream, Megatron and Soundwave and the Combaticons because they were my favourite G1 characters. Unless the toys seem really "cool" or interesting to me on their own (I bought a lot of the Japanese Beast Wars toys for this reason) or at its worst, I like the paint job and tech specs. If I was rich beyond my wildest dreams I might become a completist, but that is unlikely to ever happen for any number of reasons.
The only time I continued collecting something despite intensley disliking the current quality of the product was Spider-Man comics during the Clone saga to the Byrne/Mackie run. And that is because at the time I could not imagine my life without Spider-man in it (now lets not interpret that the wrong way!).
Catcon: sleeper agent of evil