• Buying locked phones is a BAD BAD idea
• Getting something as close to stock android as possible is a good idea. The further something goes away from stock android, the more I personally hate it.

Don't be an idiot. Do your research before making a big purchase. There is no such thing as Android vs iOS. There's Samsung vs Motorola vs Xiaomi vs Apple and so on.

Brands to avoid in my opinion:

• Samsung. So much bloat on their phones ugh. I don't like one ui (their android skin). Also, as someone mentioned, they're the Applest of non Apple brands.
• Xiaomi. Same problems that Samsung has, except their UI is eeeeven shitter. The cluttered ui (which seems to be quite present in Asian origin software) gives me a headache.

Now I don't want to endorse any given brand cuz fuck corporations. BUT, if you're looking for Android, I'd recommend going for brands with stock/almost stock android on their phones.

Don't fall in the "Xiaomi just has better hardware" trap. It is true that Xiaomi tends to pack their phones with more capable hardware. BUT holy moly is their software so so so bad. If your phone isn't your main computational device, then "not the best hardware for the price" is not going to hurt, trust me.

IF you want to flash custom ROMs then Xiaomi phones could be a good deal. But again, you're kinda inviting some headache. If you unlock the bootloader, you void warranty and all that. I used to do that when I had a Xiaomi device. But couldn't keep up and just got a stock android device when the Xiaomi one broke down.