Which Iphone should I get? - 2

I have had my samsung galaxy s6 for 2 years now but the battery has gone to ****. I have never had an IOS device and I have had my share of android so no I don't want another android device. I've been looking at the iphone x but the price offsets me. I can afford it but I really don't think t's a good thing to use 1k on a phone. I heard good things about the Iphone 8+ but bigger phones never called to me. I can probably deal with the size if the features are worth it. Lastly I thought about the Iphone 8 but then I read some reviews about it being only 750 quality and that it was basically the same as an iphone 7. So which Iphone should I get?

Iphone 8 plus or apple watch?

I don't know what i should ssk for

Added (1). i don't know what i should ask for for christmas? Already have an iphone 6s kinda want an upgrade but an apple watch seems cool

I don't know what's wrong with my iPhone 5?

I recently got my iPhone 5 fixed as I accidentally dropped it and smashed the screen. It has been working completely fine until just now when a dark purple colour wiped across the screen and turned the whole phone off before restarting itself. It just happened again as I'm typing this.

Any advice?

Added (1). It keeps on happening now whenever I try to use the phone. Also, the battery is constantly jumping up and down.