Which gear take on a route like this is quite a personal decision, but if someone tells you that the less weight, the better, pay attention.
I carried a lot of clothes, because I had extended my stay both before and after the trip, and also the SLR camera with its lens, all quite heavy, and finally I had to buy a small backpack and hire a company that I would move the big one. I think the backpack weighed me about 15kg, roughly. A few months later, doing the Saint James Way, I weighed only 7 (in fact, it was the lightest backpack of the whole group that we were doing over the days).
So basically the equipment you carry must meet the following three characteristics: it must be light, waterproof and quick-drying.
Waterproof is non-negotiable, because sooner rather than later, it will rain. Lightweight, more negotiable, if you plan not to load your backpack. And fast drying is recommended, sometimes the same wind will dry you out, if it stops raining before you finish the route; if you sleep in hotels, the same warmth of the room will help; but if you sleep in tents, bothies, or similar inventions, you may still find your clothes wet the next day.
That the clothes have to be technical, I guess you’ve all taken it well already.
I am one of those who carries 2 trekking poles. I highly recommend them. You should also think about gear stuff like gloves, hat, neck gaiters, sunglasses …
Given the hardness and irregularity of the ground, I recommend half-cane boots, which will always better protect our ankle. High cane boots I think it is not necessary, since many miles have to be done and we will have more rigidity. In addition, the terrain does not require a boot of this nature.
As I mentioned before, the West Highland Way runs through one of the wettest areas in Scotland, which in itself is already rainy, so I totally recommend that the boots be Gore-Tex. If you sweat too much, you can always put talcum powder on your feet, to keep them dry, or any other product intended for this; a pair of leggings I don’t think will help keep your foot dry for too many hours, but it would be an option if you are unable to wear Gore-Tex.
Finally, the sole should provide us with good grip and good traction, as we will find wet and muddy terrain. It is therefore recommended that the soles be Vibram, Contagrip or some similar technology.
I like a lot Salomon, so if you’re into “classic” leather boots, I would recommend, for example, the Salomon Quest 4d 3 GTX, which are available in both men’s and women’s models. If you prefer lighter ones, Salomon X Ultra 3 Mid GTX will serve you, also in male or female model.
We must also take into account the men and women socks, which must fit well on the foot, without wrinkles or moving, having a good padding, especially on the toe and heel, they must sweat well and dry fast.
For me, the best solution is to combine warm and water-repellent trekking pants, such as these Izas for men or these others for women, which if the rain is thin or seems to last a short time, they will hold up without getting wet, with waterproof pants or covers, such as these for women and these for men. They are inexpensive, take up little space, and are put on and taken off at a time. Of course, low breathability can be a factor against it, although thanks to the Scottish cold, the legs do not get too hot and do not get wet from sweat.
There is also the option, of course, of waterproof pants with Gore-tex membrane or similar, but it shoots up the budget, especially if more than one is needed.