Well, if you want stuff to end up on the site, then you pretty much have to use some kind of Finale product.
Personally, I quite like using Sibelius, probably because that's what the school's got and that's what I first learned to use. I especially like how the note entry system is essentially based around the Numpad. I think it's a little harder to learn how to use but it ends up being faster in the long run. It's got loads of features and they're not hidden in special menus that only pop up when you select a tool. Having said that, it's not cheap (the same price as full Finale) and it doesn't come on different versions ranging from limited to full features which, depending on how you take it, can be a good or a bad thing.
There was a period where I used to do all my arrangements in Sibelius, export them as Midi files and then tidy them up in Finale because I found the note entry system so slow.
But like I said, if you want your stuff to end up on the site, you'll need something from the Finale family of products.
