I prefer Auction or Buy it now format.
As a buyer, I never make an offer on a domain. You have a domain for sale? Well, let me know what is your price or at least, give me some minimum offers indications. If it is a plain "Make offer" and no price indications, I ignore even if its a domain falling exactly in my category.
As a seller, I always do auctions or Buy it now. If I have a make offer format, I will at least indicate the minimum offers I am willing to get. It saves everybody's time.
I always get best results with Buy it Now format. Auctions are often deceiving on a small marketplace like NamePros. You never know if the buyers will show up in that 48-72 hours auction period. As a buyer, NP is amazing to get super deals.