Well i use Omnipage. I had a free (le) edition with my Canon scanner, and then i got the complete package. Not so sure its the best, but i have not found any limatations with it yet.
I use it to scan in Articles i want to keep from magazines, and i scan all my college work in with it, all 100% accurate.
There is one problem i have found, which can be got around...
If you dont set areas and other parameters, if there is "background" text in an image or the likes, it does ocr on that too.