I've been using the Monroe Quick Struts for a couple of weeks now. Not a lot of time I know but this what I've learned so far. They are very compliant, and soak up small sharp bumps like pot holes and frost heaves very well. They control the car very nicely over large bumps at high speed like you sometimes find on highway interchanges. They feel a bit softer than the OEM struts on my 2002 GT but not by much. I know that the struts have a lifetime replacement warranty from Monroe so leakage is not a problem. As to OEM or Delco it was a matter of cost, not just in parts but overall including labor. Getting the Quick Struts significantly reduced the cost of installation. My total bill installed was ~$1100. So far (fingers crossed) they are working out fine. Having said that it is no longer a "performance" suspension but rather one biased towards comfort. By the way my car has stock rims and Goodyear Assurance Triple Tread tires.
Keith