I certainly prefer the original floppy issues to collected editions, but as others have written, there are advantages to TPBs and other collections.

It's hard to take 20 or so floppies to one of my daughter's swim meets or when I'm on the road for work, whereas a TPB is perfect in both portability and durability.

As well, as Confessor wrote, there is a cost component. I have the first two X-Men, the first Avengers, and the first FF Omnibus editions, simply because I am never going to want to or be able to shell out the kind of money to acquire all of those stories, but I still really want to read them. Same with all of the Avengers, Iron Man, and Thor Masterworks; the stories are the same, and they cost me a fraction of what the individual books would.

Lastly, there are some series that definitely read better when collected. I own the entire run of Fables in TPB, and quite frankly, I don't know if I would have survived reading it one monthly book at a time. However, when an entire storyline was collected, it all flowed together and I could ingest as much of it at one time as I wanted.