Ulefone are right up at the top of this market segment. Their devices look cheap, but they are generally very durable and they work really well. They have figured out VoLTE and VoWifi connectivity globally and they shift a LOT of units. Cameras are pretty decent but share the same caveats as everyone else here. Battery is generally stellar and they should last you a good couple of years. BEWARE the tick, tick, tick, TOCK cycle. They release a lot of underspecced garbage and it can sometimes be difficult to tell what is their actual flagship. Their warranty SUCKS, but you shouldn't need it unless you abuse your device. Extra points for making them impossible to kill on the software front too. When unlocking bootloader, rooting or flashing custom firmware Ulefone have baked in a hardware level safety net that can bring a device back from the absolute brink of death. Scenarios that would guarantee a brick on many other devices, you can ALWAYS flash back to factory state with an Ulefone. They're the kings in that area.

CAT I would not bother with at all. You are paying for the brand, but underneath it is the absolute bottom of the barrel hardware dressed up in a premium image. They're shite, and they fall apart to boot.

Blackview is a weird one. I have major trouble picking which of their releases are decent and which are not. They HAVE released some stellar devices over the years, and they have been around a long time but they have had some massive failures and then failed to provide any warranty or support for those that got unlucky. Screens spontaneously cracking, bits falling off, screens coming unglued, failed waterproofing etc etc. And then next quarter they will go and release something with zero flaws. Too much of a risk for my liking, but I have been tempted by their recent small form factor rugged phone. It looks great.

Doogee, Umidigi, IIIF150, Unihertz I would not touch again with a ten foot pole. I would not be at all surprised if these brands turn out to be subsidiary of one of the more successful manufacturers where they use their poorly binned chips and scrapped body designs. They're cheap as shit, but they are pretty disposable. If you want a cheap bag of problems, that nobody will help you with...go for it.

AGM is an interesting case. I own their current flagship offering and I've described that experience in detail above. They have traditionally positioned themselves as the premium offering in the rugged space. Snapdragon processors, extremely high quality body manufacturing and a generally very premium feel with a price to match. They do not shift as many units as Ulefone, but they offer a physically far higher quality product. That lack of scale comes with a few issues on the software side, but in reality it is rare to see a major version update from any of these manufacturers and AGM have actually addressed several release issues via firmware updates. It's tricky business for AGM. They have recently joined the rest in releasing low BOM devices to allow them to keep producing a true halo product when they can. When they do, the price tag at first glance makes them seem completely unappealing: why pay double the price when the feature set seems comparable to Ulefone or Blackview? It's not the same experience. AGM actually have a real warranty which I have used, and they have real customer support agents. They worked directly with Qualcomm to build me a firmware that would get VoWifi working! You will not get that from any of the others, and it won't feel the same when you pull it out of your pocket either. They are certainly not without issues, but it's the best experience I've had to date and seems to be the only rugged brand dealing with Qualcomm. Be warned. They are steadfastly against unlocked bootloader, root or any other software mods. I doubt it will ever happen, their stuff is locked down HARD.

If you are in the USA, it would also be worth looking at what Kyocera and Sonim are up to. Both are priced relatively high, and for Kyocera I think they occupy much the same space as Samsung with the xcover line: not quite fully ruggedized, but certainly good enough for most people. I had a Kyocera back when 3G was sufficient and it was a GREAT phone. These days with VoLTE and VoWifi basically being essential, it's not really an option for me anymore but if they entered the market here in Aus I'd jump ship. They're great. Sonim tend to be pretty far behind on specs and super expensive, but they are pretty much impossible to beat for signal and durability...again same issues with IMS features internationally.

Well, that's about all I have to say about that.