At the risk of being downvoted to hell
You could get an iPhone from Apple, John Lewis etc. Unlocked and sim free.
You get the updates from Apple and there is no carrier bloat.
Yes, I know this is heresy but the poster asked a question...
There are some Android equivalents that others will be sure to mention.
don't buy your phone from a carrier. go for SIM Only deals on say a 1 month rolling contract. Then when the carrier pisses you off, you can move to another without the unlocking hassle.