Do you need the in room kitchen facilities (or laundry if a 1br or larger)? That is the only reason to really consider a villa. The costs of booking them directly are vastly more than the equivalent regular rooms at the resort. A Standard View Studio Villa at AKL Jambo House was $633 for NYE last year, while a Standard View room was $537 for the same night. A 20% markup for a mini fridge and microwave. You won't get any other perks outside of that.
You could consider renting points from a DVC member to book a villa, but you don't get daily housekeeping that way.
Reason to narrow your choices? What do you need at your resort? Value resorts are minimal in their frills, no full service restaurants on site, etc. Moderate resorts are a step up, larger rooms, pools should have a water slide, most have a full service restaurant, etc. Deluxe resorts are all indoor hallways, even yet larger rooms, more amenities onsite, and most offer multiple forms of transportation. Prices go up accordingly. If you are only planning on sleeping at the resort, and spending the entire day in parks, most people would opt for a value resort as they view it only as a bed. If you may spend time at your resort, or want a slightly quieter experience (most youth sport teams stay at values) then look at a moderate. If you plan at possibly spending multiple days at your resort, or want things like a gym onsite, then you look at a deluxe.