It depends. Do you care about any of your 100+ PS2 games? Will you play them again?
The TIV for old PS2 games (especially disc-only variety) is pretty low, so you likely won't get much in trade from a retail store. You'd get more money parting them out to individual parties.
If you don't care about any of your 100+ games and likely won't play them again, you might as well get rid of them altogether now while your local stores will take them.
If you do think you'll play your old games again in the future, you might as well keep them. It would be difficult to buy them again for what little you'll receive for them in trade from a retail store. And as they're disc-only copies, your 100+ games won't take up much shelf space at home.