Which is better? Quarentine or Delete?

I've been using a lot of programs to keep my computer at it's best. sometimes programs will give me the option to either delete a file or quarentine it. I was wondering which is actually better in the long run.

 

If it's infected I would delete it but if your not sure about the detection I would just quarantine it. When you "quarantine" an item it dis-infects and moves the file to a safe place where it can no longer re-infect the system.