quick poll:
dual monitors or 1 ultra wide for coding

Unpopular opinion: Doesn't really matter as long as ultra-wide supports dual display mode

Why not both?

At least two. Also, one of them in portrait mode for documentation, logs, debugger, linux console.

Always more than one over one large one its easier to manage whats taking up real estate

I really really love my ultrawide, however I use it with my laptop, so I still have 2 screens on my setup, I think it comes down to trying it out to determine if you like it or not, I got to try it out at an internship before I bought one

The standard laptop screen is more than enough for me.

Dual portrait

I find managing my programs/windows on a multimonitor setup way easier but that's only my opinion

Dual