What causes trench foot is not socks, but rather constant immersion of the feet in wet and cold conditions. If your feet are immersed for a length of time, socks most likely aren't going to do jack. The best possible prevention for trench foot is not necessarily just the quality of socks, but rather keeping feet dry: In both WW1 and WW2, British troops were issued gumboots (wellingtons) for use in static roles (such as manning trenches or artillery positions) to give much better protection to the feet from immersion than the normal issue British ankle boot.

Gumboots though are not a solution: They aren't much good to a soldier in a mobile or offensive role, and are awkward to fight in, and are not guaranteed protection. If dry feet cannot be guaranteed, the only substitute is to ensure good foot care: The British Army in WW1 went to great lengths to place checks on soldiers feet: In wet trenches, soldiers were expected to change socks daily with dry replacements, and as well as this, soldiers were ordered to smear feet in a water repellent grease derived from whale oil. Foot inspections were also carried out to ensure these instructions were adhered to and punishments were given for not doing so. The other important factor was troop rotation: Although I can only speak from the British perspective, WW1 soldiers spent far less time in the frontline trenches than people imagine, with units being circulated from the front to second and third-line trenches and through to rear areas fairly regularly. Ensuring soldiers had rest periods in dry conditions was an important factor in preventing trench foot.

The more mobile nature of WW2 meant the average soldier was less likely to spend front line service constantly immersed in water, but the issue did not go away, and when battles were fought in wet conditions trench foot and the need for good foot care would become apparent. Eugene Sledge, who fought with the 1st Marines at Pelelieu and Okinawa, mentioned in detail in With the Old Breed how the brutal fighting and miserable wet conditions on Okinawa made good foot care difficult:

Most of us had serious trouble with our feet. An infantryman with sore feet was in miserable shape under the best of living conditions. During a period of about fourteen or fifteen days, as near as I can calculate the time (from 21 May to 5 June), my feet and those of my buddies were soaking wet, and our boondockers were caked with sticky mud. Being up on the line and frequently shelled prevented a man from taking off his boondockers to put on a pair of dry socks. And even if he had dry socks, there was no way to clean and dry the leather boondockers. Most of us removed our mud-caked canvas leggings and tucked our trouser cuffs into our sock tops, but it didn't help our feet much. Consequently most men's feet were in bad condition.

My feet were sore, and it hurt to walk or run. The insides of my boondockers gave me the sensation of being slimy when I wiggled my toes to try to warm my feet with increased circulation. The repulsive sensation of slippery, slimy feet grew worse each day. My sore feet slid back and forth inside my soaked boondockers when I walked or ran. Fortunately they never became infected, a miracle in itself.

Some time later, after Shuri castle was taken, Sledge got a chance to properly inspect his feet.

We dug in as a secondary line along a low ridge with some ruins of Okinawan houses behind us and a broad open valley stretching south to our front as far as we could see. The rain ended the night of 5-6 June. I'll never forget the sensation of profound physical relief when I removed my soaked, muddy boondockers for the first time in approximately two weeks. As I pulled off my slimy, stinking socks, bits and shreds of dead flesh sloughed off the soles of my feet. A buddy, Myron Tesreau, commented on the overpowering odor, only to discover that his feet were just as bad. My socks, a pair of khaki-colored, woolen army socks (thicker and heavier than our white Marine Corps issue) were so slimy and putrid I couldn't bear to wash them in my helmet. I had traded a candy bar to a soldier for them back in April. They were my prized possession because of their comfort when wet. With regret, I threw my prize socks aside and spaded dirt over them as though covering up a foul corpse.

It was great to wash my feet, holding them up on an ammo box to let the sun shine on them while I wiggled my toes.Everybody got his feet clean and dry as soon as possible. Mine were extremely sore and red over the entire soles, almost to the point of bleeding. All of the normal friction ridges of the skin had sloughed off, and the soles were furrowed with deep, reddish grooves. But after drying them in the sun and putting on dry socks and boondockers, they soon felt better. Months passed, however, before the soles appeared normal again.

The real advantage over footwraps that socks would hold in such a situation is utility: Socks can be changed and feet powdered far easier than when you have to meticulously re-wrap feet.