It really depends on personal preference. Identify and think about what aspects of your phone you use most, need most, think are "weak" on your current one,....
- Camera: do you use your phone to take pictures? Do you take a lot of pictures? Do you want them to be "good enough for facebook" or "good enough to make a printed album"? Do you find a good zoom important? My last phone had a really good camera system, and I seriously miss it and its capabilities - on vacation I've gone back to using an actual separate camera because my phone's cams just aren't good enough for me. On the other hand, my wife doesn't care much for the quality other than "good enough for an instagram post" and cares more about the selfie cam than about good zoom or stabilization.
- Battery life: are you a very heavy user and/or do you want to be able to go multiple days without recharging? My current phone, I can usually last 2 days of use (videos, spotify, GPS, taking pictures, surfing, etc) and still be somewhere in the 20+% left, which I think is great. My last phone had half the battery and twice the power usage (exaggerating slightly). I had to recharge it every night - still not too bad. The battery in my phone before that one had started deteriorating; if I was making longer trips I had to bring a power bank or it'd be dead halfway through the day. For my normal use I could just plug it in at my desk, or in the office, or in the living room, whatever, but still it got annoying. A lighter user would probably still be OK with that last one since it'd still last them a day or so.
- Screen quality: do you really ever use your phone for serious video watching? If you're using it to surf online and watch the occasional YouTube video, it won't really matter all that much - YT limits quality anyway. If you use it to watch full HD movies in bed or full TV episodes while on the bus or whatever, you'll want something better.
- Likewise - screen type. Very much personal preference: do you mind a reflective screen which may be harder to use in sun glare? Or do you dislike matte screens where colors are less vibrant? Do you mind if the camera/microphone take up a small part of the screen?
- Brand and support: do you have a principled stand against or for specific brands and business practices? Or do you really like/dislike certain OS choices? There's initiatives like the Fairphone or Teracube, while some big brands have been pushing some of their later models as being exceptionally "green" (iPhone 13 pro for example). On the other hand, some people principally will not use non-Android phones because of habit or preference. Or they're locked into the Apple or Google ecospheres. If Android - do you want stock? Or hate it? Some brands really change their OS around a LOT. I now use a One+ which comes with pretty much stock Android, no bloatware, no additions, no nothing. Certainly has benefits, but also limitations. This also ties into support and longevity: stock Android will keep getting updates. If you're using a Samsung S22 and Samsung decides they're not releasing new updates for that phone after 2024 - well, sucks to be you. My last phone was a Huawei - great value for money...But the newer Huaweis don't have Google support anymore, meaning no Gmail, no Maps, no Play store, etc because of American anti-espionage/protectionism laws.Which made the phones a no go for me.
- Storage: do you plan on downloading or making a lot of movies or games? Do you want to be able to port them? Having a large internal storage has its advantages, but having a smaller internal storage but a slot for microSD cards can be even more practical. Do you want/need a dual SIM solution (work and private phone numbers on one machine, a US and a Canadian SIM because you're often crossing the border, SIMs with different providers to allow switching in areas where one or the other has worse coverage), or is this completely unimportant for you?
- Build quality: do you care? Will you buy a case to protect it? Do you want/need waterproof capabilities? Just splash water proof for when you're washing your hands, or full submersibility for when you drop it in the toilet (or go swimming with it, I guess)? Do you prefer glass back covers, metal, plastic? There are benefits to all of them - "plastic" doesn't have to mean "looks and feels cheap".
- Build choices: do you have a strong preference for the finger print sensor? In the screen, on the back, on the side - all OK but some people really hate one or the other. Likewise, do you care about an audio jack? Or do you use BT earbuds anyway? Does fast charging or wireless charging matter for you? Stereo sound?
You'll never find a phone with the perfect camera setup, unlimited storage, two SIM slots, a 4K UltraHD OLED screen, battery power for 5 days, fully waterproof, with exactly your personal choice of OS, a full Bose surround sound system, and all that for $2.50.
Like any larger purchase, if you're not up against a wall as in "my phone broke and I need a new one tomorrow", take your time to consider different angles and aspects, and try to make a list of must-haves, nice-to-haves, willing-to-compromise-on, unimportant, deal breakers. I'm sure I've forgotten some aspects that I either don't care about (looks of the phone) or consider trivial/obvious (does it use the right type of plug for my country) or whatever.
Once you've figured those out, you can start comparing (reliable) comments and reviews, use some online questionnaire to help narrow it down, etc.
