Depends on what you want to use it for.

You won't find any Sibelius files on this website, all the tabs on here are either standard, ptb or gp format.

If you mean for writing down music, Sibelius is better for orchestras, or any form of music that uses more than guitar, bass, keyboards and drums.

Guitar Pro is good for writing down rock music, sometimes jazz & blues but when it comes to writing proper scores then it is useless.

Edit: So if you plan to go write rock music, then definately (IMO) go for Guitar Pro. If you want to write for alot of instruments, and print it out for use, then Sibelius is your best choice.
Guitar Pro works with sheet music as well as tabs.
for fans of...

Motion City Soundtrack, Get Up Kids, Jimmy Eat World, Transit, Brand New, Dashboard Confessional, Early November, Fall Out Boy, Jawbreaker, Polar Bear Club, The Story So Far, the Wonder Years, Something Corporate.
Like Regression said, Sibelius is more an orchestral instrument tool. I believe some of the pay tab sites use a form of Sibelius but if you just want to learn guitar songs you would be better off getting Guitar Pro.
Quote by Mia (Pulp Fiction)
Why do we feel it's necessary to yak about bullsh*t in order to be comfortable?

That's when you know you found somebody special. When you can just shut the f*ck up for a minute, and comfortably share silence.

Sibelius is more an orchestral instrument tool

But Sibelius G7 is more of a guitar tool.
It's pretty similar to Guitar Pro, you have the tab, notation, the guitar fretboard at the bottom, but with the usual Sibelius controls.

Out of the two, I do prefer Guitar Pro, it has the features you will need, plus it's like a third of the price.
we use sibelius in my composing music with technology and it sucks IMO. i have guitar pro and it is SOOO much better
schecter hellraiser c-1 fr
GAS list...
Mesa roadster with 2/12 recto cab
PGM 301
98% of teens have been around or have had alcohol. Put this in your sig if you like bagels