Ah, good, the old pilot watch debate.
If you want pure functionality and ruggedness, and nothing else, Casio G-Shock. I have one. I use it regularly, especially when I'm outdoors. I also wear it when flying, usually airman certification activities in little airplanes.
If you want a beautiful piece of equipment -- "male jewelry," let's be honest -- which is also highly functional in an airplane, Omega Speedmaster. It's as close to a perfect watch for flying as has ever been made. They have been worn by pilots for many decades. I actually have two - the "Moon Watch" as well as the "Broad Arrow."
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Speedmaster is a no-nonsense watch, pretty much bulletproof. Other than a "tachymetre" imprinted on the bezel, it's nothing more than a standard watch with a chrono. Everything you need for flying. I've owned mine for 21 years. It's about to go in for its first-ever overhaul as it's starting to lose a few seconds each day. It goes back to Omega for that. It looks brand new... these things really don't "wear." Just get it cleaned once every five years or so.
The Broad Arrow is a Speedmaster with a zulu hand and and a date function. I had always wanted a zulu hand, so when the Broad Arrow came out years, I actually joined a wait list for it. It took a year and a half for it to be delivered. I don't think the watch ended up being very popular because it doesn't seem to be in the inventory anymore. Maybe one day its relative scarcity will prove to enhance its value.
The funny things about "fancy" watches and all the negative comments they tend to garner is that, as far as investments go, they can be pretty solid! I paid $2000 or so for my brand new Speedmaster in the late nineties, and as a used watch it would go for $3500 or so today on the open market. I could get $4k for it on trade for another watch. Yes, there are far better investments out there, but this is a pleasure buy.
I have owned a number of other watches. Among them were a Rolex Daytona, and an IWC Pilot's Watch. Same thing. I owned them and sold them either for what I paid, or a bit more. I don't think I've ever actually lost any money on a watch. If I did, it would be pennies on the dollar. I could liquidate my current two watches, my Omegas, and be right back where I started, even accounting for inflation, or maybe a little ahead. One could do far worse. When it comes to the finances of watches, I just view it as an exercise in parking cash. You're not losing any money, you're just storing it... on your wrist.
This is definitely not true of all watches. Breitling is an example. Breitling's quality has significantly improved in the last decade, but they do not hold value. Breitling is still battling an image problem -- namely, they started their company selling watches with high end "looks" but with quartz movements. Their watches cater to an image-based buyer. I've never thought of Breitling as an aviation watch manufacturer, I've just thought of them as an aviation watch marketing agency. Most of the extra features in the aviation watches they produce are not very useful in real world applications, for most. (There are exceptions.) A truly good pilot's watch is pretty basic, easy to read and operate, and arguably has at least a chrono in addition to basic hour/minute.
It's all fun to discuss and debate. There's no right or wrong. But I've never used an E6B built into a watch. Why would I? I have my iPhone with the "my E6B" app in my pocket. Far easier to use. Let the watch be beautiful AND functional. Adding a ton of doodaddery onto the thing doesn't make it more functional. Makes it less so, in my humble opinion.
And one last comment, for the inevitable one-liners from folks who just think the whole thing is ridiculous, that is a perfectly valid view. But flying is both and art and a science, and to watch aficionados, watches are art. The movements are spectacular, hand-made creations with incredible precision and they're enjoyable to watch in action. In the same way that the human race celebrates beautiful music, beautiful art, and beautiful machines, those of us who love watches do the same when we strap one of these beauties onto our wrists.