What next

[Evader115]

I just bought an m1 mbp and have $330 left over in my budget, I a looking to buy either an apple watch (4 or newer) iPad (sidecar compatible), or a new phone.
I have a 6s.
I am looking at used.

 

[Apple_Robert]

Which would you use more on a daily basis, a watch or phone? I use my watch more than my phone.

Side Car is nice although I suggest you go with 11".

 

[velocityg4]

That'll get you a used iPhone X or iPhone 8 Plus. Which are a pretty decent upgrade from your current phone. Either Amazon renewed. Just choose your seller carefully. If it's scratched up or the battery is worn out. Just send it back.

I'm quite happy with my renewed iPhone XS.

The watch seems like something to get after you get a nicer iPhone. At least in my opinion. Same with an iPad.

Although for the iPad. I'd wait for the Apple even tomorrow. To see if there is a new one. What it offers. Plus if it is still $329. Which can often be found for a little less.

 

[Toutou]

apple watch (4 or newer) iPad (sidecar compatible), or a new phone

Are you happy with your phone?
Would you enjoy wearing a smart watch?
Do you have a use case for an iPad?

Those are very different devices for different purposes, how can anyone give you any meaningful advice?
Unless you feel a strong desire to own and use one of the devices I'd advise you to consider saving the money, treating yourself to a few fancy dinners, donating to a good cause, going on a road trip and other pleasures.