PX Nanolight vs Look Ultra 585

Hi, looking for some help and advice. I'm looking at some second hand frames, with a few to building up another bike. I've the option of either a PX Nanolight (not the new frameset, its the mark 2 version) in immaculate condition - I've seen it, its like new tbh. The other frame, a friend of a friend has it, its a LOOK 585 Ultra. Sizings are similar enough. Of the two, the Look is the older frame. Moneywise, they are similar in price. Can I get some feedback/advice from your good selves - anyone ridden either of these, what did they think of the frames? All info/advice be greatly appreciated.