What's the best material for privacy fencing? Wood or vinyl?

If you want the privacy fencing and do not care about its cost, there is only ONE choice. Vinyl fence. Look around and shop around for material and prices within since they come with all different quality of thickness and guarantees, not every vinyl fence materials are made the same way. If you just want to go cheap material that is less costly, then go to Home Depot, but for posting you would still need to buy 4 x 4 for each.

The "best" material may have different meanings depending on your values. Although vinyl/PVC fencing does require less maintenance it also has several disadvantages. It will melt/burn when exposed to fire, may crack if hit in severe cold, and is one of the most environmentally unfriendly products there is.

In order for a manufacturer to provide you with a PVC fence that does look like new for such a lengthy period of time they need to add stabilizers to the "plastic". Many of the stabilizers they use are highly toxic and may include lead or cadmium. Perhaps you remember the recall of rigid Vinyl mini-blinds about 14 years ago because they were causing lead poisoning in children. Once that fence does need to be replaced there is not a very well established recycling system for PVC in place so it will end up in a landfill.

The main concern with cedar fencing is the maintenance requirements to keep it looking "good". If you do not mind a weathered look then it should easily last 10+ years with little maintenance. There are after all houses/barns with wood siding that are still good after 50+ years of exposure. The two biggest enemies with cedar/wood fencing will be UV degradation of the wood fibers and moisture. With the cedar fencing you do not want the bottom of the fence to be in direct content with the soil otherwise it will accelerate it degrading and cause staining. The PVC fence they can rest right on the ground without that concern. If you don't want the weathered look then you will have to paint/stain more frequently to keep it looking good. I have seen cedar fences last 20 years and counting. The problem was that until relatively recently you also used cedar posts which would rot out in 5-10 years and you end up having to replace posts.