I'll post from my experience and break it down by category:
-Quality USGI 250 rd belts will run you about: $40-50 each.
-Links will run you about $20 per 250 rounds
-Using a 1918 loader, I can load a 250 rd cloth belt of 30-06 in about 10 minutes. The 1918 loader was designed to load 30-06 and 30-06 works perfectly in the 1918 loader. I have never been able to get .308 to work reliably enough in the 1918 loader.
-I can load a 250 rd. linked belt in about 25 minutes using a push/pull linker machine.
-I use links for .308 and belts for 30-06. I would personally use belts for .308 if the 1918 loader was reliable with .308.
-Hand-loading belts or using a single stage manual belt loader is far too time consuming (1-2 hours for a 250 rd belt)
-Hand-loading links is only for those that love to endure pain.
-In the two 1919s that I own, I have found links and cloth belts to be equally reliable. One note of caution is when using a trunnion protector, it reduces the clearance in the feed-way, and with some guns the clearance is too tight for links to feed reliably.
-There is no doubt that using links will subject the feed mechanism to more wear than if cloth belts were used.
-Both will last dozens of loadings.
Retrieving links/belts after shooting:
-A belt can be picked up in a few seconds.
-Picking up links takes a while
-For belts, just throw them in the washing machine and let air dry. Do not use bleach, it will deteriorate the cotton.
-For links, when they get dirty from being on the ground after firing, I throw them in a bucket and soak them in water with Dawn detergent. I let them air dry and spray WD40 on them afterward and store them in a plastic bag.
Overall, I prefer belts due to much faster loading w/ the 1918 loader, less wear on the gun, ease of pickup after shooting, and ease of belt maintenance. If I did not own a 1918 loader, I would use links, as hand-loading belts or using a single stage manual belt loader is far too time consuming.