I set aside some time to work on my favourites, it starts off empty.
1) show clones in main game list
2) start at the top of the list and work through the games, maybe doing one letter per session: IE Im going to to the 'A' games tonight - maybe add 10 games to your faves, then switch to the faves list and whittle it down to the essentials that fit your criteria - give yourself sometime to play each of the games a little and make an informed choice on what you like to play today, not what you liked to play 25 years ago.
3) rinse repeat
4) once complete, prune the gamelist or add new games as you discover/remember them
If you think about it, with over 8000 games (inc clones) its a much less daunting task to add 100 from nothing, rather than delete 7900 from 8000.