I like French paratrooper boots from the 1950s. It's kind of like those expensive Red Wings work boots but with a double-buckle gaiter for blousing your pant legs, and much cheaper, like 40 - 60 USD for an unused pair, and you can still find them pretty cheap from French surplus sites or a bit more expensive from American resellers.
The official designation is BMJA Mle 1952 or BMJA Mle 52/59. There were several different manufacturers, all producing identical boots except for the manufacturer-specific tread pattern, but Belle Donne of Grenoble and the French subsidiary of Wood-Milne seem to be pretty common.
In France, this entire category of milsurp boots is called "Rangers", and were a popular surplus item used as hiking and work boots, prior to the proliferation of affordable modern footwear.
I'm not entirely sure why, but they are still fairly comfortable to wear during hot weather, compared to other leather boots, even during heavy exertion or running.
There is also a later and more common 1960s model called the BMJA Mle 65, which was manufactured up to the early 2000s, but it only comes in black color, which I imagine would be worse for hot weather.
The only bad thing about Ranger boots I found is they can be painful to break in and wear comfortably until you develop calluses on certain part of your foot, especially the Achilles' tendon part of the heel, to the point that the French conscripts had an expression that you break the foot to the shoe, not the shoe to the foot (c'est le pied qui conforme a la chaussure).
Also there is a specific French Army "regulation" lacing technique that makes the boots much quicker to put on and take off, and more secure than a standard lacing and knotting. Surprisingly there is no knot-tying involved - it's weird at first but easy to master.
The leather uppers of the boots are pretty durable and seem like they will last forever, even though they are already decades old. Although I did have to clean and oil/grease the leather on all my boots to recondition it after decades in warehouse storage.
I also like surplus French "pataugas" jungle boots (official designation "chaussures de brousse"), which are very comfortable for hot weather and wet/humid conditions. They have a canvas upper, rubber sole, and hemp insole, which is very breathable and dries quickly if it gets soaked.
I don't think there are any official model number designations for pataugas boots, since there are many different versions and variations made by many different manufacturers, but the most affordable surplus are 1990s - 2000s production runs of older 1970s - 1980s models. These can still be found as low as 20 - 30 USD for a pair. One time I even got a pair for 15 USD, in mint/unissued condition.
I prefer the 1970s type with Ranger-style gaiter and buckles like this type, made by Wissart:
The pataugas type boots are a popular enough modern fashion and sportswear item that there are some brandname shoe companies like Palladium that specialize in modern production models for regular retail sale, but they are way overpriced and made in China, unlike the cheap surplus ones that were made in France with better material and craftmanship. The modern repros and knockoffs by Chinese companies are even worse.
I like repurposing a lot of other 1950s French surplus gear, like field jackets, trousers, webbing, canteens, musette bags/pouches, etc for workwear since it does have a certain vintage style to it while still utilitarian functional, but the boots definitely stand out above the rest as being better in some respects and way cheaper than the modern retail equivalents.
And I guess there is one other bit of French surplus kit that I find quite useful for workwear: the French paratroopers' Bigeard cap. I know a lot of contractors and people working in the trades just default to a regular ball cap, but I think the Bigeard cap is superior in some common situations.
It has a cloth neck cover on the back, so protects you much better from sun exposure when working outdoors. And the Bigeard cap's visor is softer, shorter, and more steeply angled downward than a regular ball cap's, so if you are working with your head in a confined space, the Bigeard cap allows you to fit your head into much tighter spaces and you can angle a headlamp beam much lower before the visor blocks it. The shorter visor also makes it a bit less vulnerable to strong propwash and updrafts. And unlike a ball cap, the Bigeard is entirely made of soft cloth, so it's easy to fold up and put in a pocket if it's really getting in the way.
The best part is that Bigeard caps are pretty cheap and plentiful all over the world, especially those made from the French CCE or Daguet camo patterns. I bought a batch on sale for something like 2-3 USD each. They look kind of weird and ugly in a lot of surplus dealers' photos, but that's because the surplused ones from the 1990s - 2000s seem to have been oddly folded or crushed in warehouse storage, deforming them. With a little warm water, they can be easily reshaped back to the more conventional shape that you see in photos of French paras.
