-
In terms of things lasting it's worth having a look at the Android One phones since they will actually get a decent update schedule (decent in terms of Android but sadly still not as long as Apple support their devices). Best bargain phone is probably still the Xiaomi Mi A1 which will easily cope with everyday things like Instagram and Whatsapp, although check with your network whether it will be supported; think one or two people here have it and rate it? The aforementioned Nokia 6.1 is a bit more but is also built like a tank if that's important to you.
Outside Android One Sony have one of the better track records with updates for their devices and will generally give you a couple of OS updates at least. I saw the Xperia XA2 was on offer for Prime Day for £199 here, which seemed like a pretty good deal actually and I was considering it myself. They have more needless stuff installed on them than you'd get on stock Android but they will let you get rid of it unlike a few companies who'll only let you disable the apps, not uninstall them.
squidink-
Thanks for the pointers @squidink , I checked Prime Day here yesterday and the best deal (apart from one that was incorrectly priced for the Essential Phone) was for an ASUS Zenphone 3 Zoom. I'll look into the Xperia XA2 and I want to see a Xiaomi in the flesh so I've got some things to work on.
ricky2slicky
I'd define it as anything under $500 as the alternative would be to have to spend $1000 on the new generation of obvious smartphones are. As long as I've had smartphones I've always owned iPhones (3GS, 4S, 5S).
I have limited knowledge of the other side of the market aside from that the newest OS is Oreo. I basically want something that will last, has decent battery life, can be used well with apps like Instagram and Whatsapp. I still use a mac but I'd like to look at alternatives to try and unhook myself from the Apple teat and the things that have started to piss me off about their products.