I've used Abby FineReader v6 in the past and now use OmniPage Pro v12. Note that neither are the current shipping product versions.
I had the same issue as kiddpete with OmniPage grabbing every image file association it could at installation but didn't have any problem resetting these to other applications.
I didn't like it that OmniPage installed a bloatware text-to-speech application automatically but perhaps I missed an installation option (but I don't think so).
The only other problem I had in the beginning was that OmniPage installed a service called 'Opware' that 'broke' a couple of other applications I used, e.g. Paint Shop Pro and WordPerfect's 'Acquire' or 'Import from scan'. However, all was well again as soon as I realised what was happening and disabled 'Opware' from running at startup.
All in all, I found OmniPage to be the easiest to use of all the 'scan-to-text' applications I've tried and, in my experience, OmniPage v12 is far more accurate than Abby FineReader 6 was at the time. I tested v14 when it came but it was much more bloated than v12 so I've stuck with v12 and haven't bothered testing v15.
PS - I can't see any reason why OmniPage shouldn't work on all scanners. It uses the TWAIN driver (built-in or supplied with the scanner) to scan the text into a temporary TIFF file. The OmniPage text recognition engine then uses the TIFF file to carry out its conversion process.
Hope this info helps...