I am a set builder. Buying a factory set is much less expensive than opening packs to complete the set. But, there are a couple of factors that nearly always lead me to purchase boxes.
1. I am a bit of a condition freak. I want my sets centered (most go into albums). There have been many times I have opened a factory set and the majority of the cards are off center. I know centereing can be a issue with boxes also. I just feel it's going to take a little effort to get a mint set. I'd rather open 3 hobby boxes and have a high level of excitement/enjoyment, than open 2 factory sets to hopefully finish a set.
2. I became a collector in the 90's which means I love inserts, parallels, and general pack busting excitement. Lately in the "Hit" heavy card economy, I've been able to sell or trade a unwanted hit or parallel for tons of base cards to finish the set.
