When it comes to choosing which books to buy, what are your biggest influences? Do you often buy books you already own in another format, because of the good looks of an omnibus/OHC?
Personally, I never buy floppies. Made an attempt this summer to subscribe to the Death of Spider-Man arc, but waiting for the next issue was always so unbearable, so I quit and completely went over to hardcovers. It's the same phenomena as owning a box set of a tv series, and not having to wait a week to see what happens next.
And when you've read the latest OHC and waiting for the next collection to arrive, there's always the possibility to go off and explore something older or different you haven't read.