If it is in collections, it has already damaged your credit score. That's irreversible (i.e. paying in full won't reverse the damage done from them being in collections).
At this point, the company (not the collectors, but the originators of the debt) assumes they have lost that money. That's why they sent it to a collections company.
You now have the power to negotiate. Granted, both the collectors and the original company want you to pay in full, but that's because they both get more money that way (the original company isn't going to get the full amount at this point even if you pay it, because they have to pay the collection company. And you won't be able to deal with the company directly, you will have to deal with the collectors). However, they don't expect to get ANY of it. So, if you can pay SOME of the debt right now, you can strike a deal. You can often settle for pennies on the dollar.
If you have the $$ to pay in full, you should because you made those debts and you have an ethical obligation to do so. However, if you do NOT have the money to pay in full, you can definitely negotiate a settlement.
Honestly, at this point, I don't think that either option is "better" for your credit score (paying in full is probably slightly better) because the debts are in collection and have already beaten up your credit score.