I consider Guitar Pro to be more of a tab editor. I’ve messed around with it in the past but found it very limited for regular notation and a pain to use. I believe that if you’re looking for a regular music notation program, that is to enter notes and rhythms, the sensible way to go is with any of the 2 industry standards: Finale and Sibelius.
Personally I’ve been using Finale for 15 years now, so I can’t really comment on Sibelius although I know it is also good. With Finale you can input your regular notation and select and drag it down to a tab staff, and it will instantly create a tab version. You just need to tell it what position on the fretboard you want to assign the notes to. Of course, you will always have to tweak a few notes here and there to accommodate it to the exact fingering you have in mind.
I have to be honest though, there is a learning curve with any of these programs. You have to memorize the keyboard commands for each rhythmic value and a few other shortcuts if you truly want to write music at a pace that is not going to take you all day. There is an option to drag rhythmic values (eg. quarter notes, rests, etc) to the intended location on the staff, but again this takes forever. I use my left hand for the keyboard commands while using the mouse with my right hand to assign the location on the staff I want each note to appear in. It’s fairly fast for me at this point. Almost like typing words. The beauty of it is that you can hear the actual sound of the note as you insert it.
There are several flavors of Finale. If you aren’t doing elaborate scores, the full fledged version might be overkill. Just make sure it has the capacity to create tabs for guitar, unless you you don’t want that. I know there is a free trial version you can download: Finale Website
Let me know if you have further questions…