The Quattro Wood is a newer and (probably) more refined speaker, but the 5 offers greater placement flexibility with the rear-firing tweeter and the different subwoofer configuration. Personally, I’d go with the Quatro, but I don’t think you can go wrong with either option.
Choice of Vandersteen models
Assume the price for either will be the same. Quatro Wood(not the CT), or the 5 (not the 5a or CT). Both in excellent condition. Don't discuss alternative speakers, other than these two. Which will sound better, which will hold value better. I have Modwright OPPO 105, and NAD 375BEE amp, 150 Watts Per 2 channel.