I've used Finale for several years (starting with 2007 version) It is somewhat arcane and cumbersome, but is capable of producing some very fine looking pages. Finale also has some lower priced versions - one of them might be what would work out for doing mostly lead sheets. Generally, Finale releases a new product yearly, with one major patch in between. Runs on both Mac and PC, is licensed to be put on two computers. Unlicensed copies (after 30 days) no longer save nor print. I started using it while taking Music Theory at the local community college. New versions will read older Finale and convert to the new format, which is NOT backward compatible. If you qualify for academic discount, pricing is significantly lower on either Finale or Sibelius.
I've been considering doing a competitive upgrade to the new Sibelius, would cost me about the same as upgrading to 2010 Finale. Sibelius does not have as frequent upgrades.
Both are fully capable of producing excellent looking work. According to reviews I've seen, both have a significant learning curve, and the way to do something is not always evident.
(I saw a link posted in the Guitar forum, but posted over here since that is where the thread originated).