A shortlist of each smartphone company

Alphabetical order?

Asus produce the "Zenfone" line, which used to make sub 6" devices but those have unfortunately been discontinued in favour of the more profitable big screen devices (and not even good ones at that). They also have their ROG line, which are large gaming phones that are now pretty much rebranded Zenfones with a gimmicky LED matrix on the back. I would avoid them, as software support for the smaller phones has ended and their big ones aren't really worth it. And Asus's support is notably jot great, speaking from experience with an Asus laptop.

Fairphone is aiming to produce devices that are repairable and modular, and most of the major parts are easily replaceable with simple screwdriver. They are also working towards using more ethically sourced materials in their devices, which is pretty cool of them! They have good custom ROM support, and many of their devices can even run mobile Linux! Still a little miffed about the lack of a headphone jack though, but at least the wireless headphones they sell have replaceable batteries

HMD makes phones as well, mostly budget to midtier devices, but many of them are pretty repairable as well!

Motorola makes some neat lower end devices, and often times they retain SD card support and the headphone jack, but they are pretty unremarkable otherwise, as it looks like a lot of their budget is going towards licensing Pantone colourways. They have announced a collaboration with GrapheneOS though for a (currently) unreleased device, so maybe that will be something to consider in the future?

Nothing has some cool designs that are a bit hut or miss, but unfortunately, they usually aren't as repairable, are super AI-pilled (LLM generated apps and an AI button that can't be remapped? Really?), and their recent devices don't support custom firmwares, despite their claim to being open to the community.

OnePlus is usually pretty good, but their recent OP15 kind of dropped the ball, becoming an iPhone clone with a giant battery. The OP13 is still really good though, and it has excellent cameras and battery life too. Plus, custom ROM support! One more thing, the OP6 is old but still a neat device if you want to try out something like postmarketOS. That OLED screen still looks great!

Oppo has a lot of great devices, their flagships have recently received high praise and their midrange devices are excellent too. ColorOS isn't the best though, it looks to be about on oar with Samsung in terms of bloat (but not as bad as Xiaomi or Vivo)

Pixels have poor performance for the money, they overheat, have terrible battery life, and decent cameras. Their redeeming quality is that, at least up to the Pixel 10 series, they support GrapheneOS, as well as many alternate spins of Android, which is awesome! Most other modern phones don't support any kind of alternative ROM.

Redmagic makes some interesting gaming phones that seem to be more focused than the ROG ones, with no camera bump, massive batteries, and an under-display selfie camera, while being relatively good value for the performance you get. If you're into gaming phones, Redmagic is probably what you want to look for.

Samsung is a bit stale and their stock software is as bloated as many of the Chinese manufacturers (though certainly not the worst), and none of their recent devices support custom ROMs. They make a bazillion different models though, many of them are good value, but others, not so much.

Shiftphone is similar to Fairphone where they emphasise right to repair, but they go a step further with a universal battery between all their devices as well as physical kill switches for the cameras and microphone. The hardware is not as mature and custom ROM support is not as developed, but in the future they could give Fairphone some competition!

Sony is the one of the only brands to continue rocking headphone jacks and microSD expansion support in their devices, and they aren't afraid of a slight forehead or chin (that is, they have front speakers with no camera cutout). Their main cameras are quite good and have optical zoom as well in their highest end models, and they have pretty good support by LineageOS (including a lot of the Xperia 1 devices as well as the cheaper 10 VII). Their flagship models are very expensive though, so either go used for an older 1 series or get the 10 VII.

Volla makes some interesting phones that try to be more minimal, and you can get Ubuntu Touch on them too! If you're into that sort of thing, they could be worth checking out.

Vivo has excellent cameras for the price, and the rest of the hardware is nice too, particularly battery life. But OriginOS is very nagging and not fun to use at all, as somebody with a Vivo device. It's usable once you install something like a custom launcher, but the "security scan" app pop ups are infuriating!

Xiaomi is the Samsung of China, they make a bazillion different phones and plenty more other tech stuff too (vacuum cleaners, smart home stuff, TVs, supercar EVs, all sorts), and as for the phones, most of them are very good value for what you get, whether it's a flagship Xiaomi or a more budget Redmi / Poco device. However, particularly in the lower end market, the software is often filled with advertisements and such. It looks like their flagship phones don't have that anymore though. And like Samsung, their modern hardware doesn't support custom ROMs unfortunately.