Pi zero or 2/3/4/5 for everyday PC?

I originally had been thinking zero due to lower power consumption as I am using solar in a van which is limited.

I could probably run other types fine too but I am wondering if the increased processing power and resultant energy draw will be justified.

I am wondering what limitation might be with the zero and if they would be an issue for me at all or not.

Just want for general internet research really and watching youtube videos. Coding too here and there which would be fine with any type I got I guess.

Also I was thinking of an eink as main display but from further research it seems they don't work like that due to long refresh rates making them unusuble for that purpose is that right? I read/saw that it takes 15 seconds to refresh but that doesn't seem right since even my ereader from 2011 refreshes in a second or two when changing pages.

Processing speed/power of anything less than a RPi 3B will be minimal, I used to use a RPi 3B+ as a desktop, it was slow, (especially internet).

I soon moved up to a 4B when it came out, & still use a 4B & a 400 as desktops, occasionally, (I use thin clients & micro desktops now).

I looked into the new RPi5, but considering it required a new power supply & cables, decided the increase in speed not worth the price; but as you don't have any yet, it is worth considering.

For youtube pi4 would be ok, pi3 is a bit slow, but probably acceptable. Otherwise it depends what do you want to run on it.

A pi zero or zero2W is not designed for use as a desktop. While you can boot into a GUI desktop, performance is horrible. The zero series are primarily designed for headless server use.

The sticking point for most low power rpis is internet performance and for that purpose the performance gets better as you move up the rpi food chain. For watching videos on the internet via youtube, the pi5 is fine, the pi4 is acceptable, the pi3 your pushing it and the pi zero forget about it. For the Pi4 or Pi5, get the 8GB version. The Pi5 8GB has a list price of $79 whereas the Pi4 is $74. The power consumption of a Pi5 is up to 15W max whereas the Pi4's max is 7.5W. Now, your use case doesn't look like you will be running at full throttle so the power consumption for either will be significantly less than the stated max.
For either the Pi4 or Pi5, you should be aware that even when powered down, they are consuming power as long as they are plugged in. This can be significantly reduced by making certain configuration changes as explained here:

https://www.tomshardware.com/raspber...er-consumption

I looked into the new RPi5, but considering it required a new power supply & cables, decided the increase in speed not worth the price; but as you don't have any yet, it is worth considering.

You can use your old PI4 3A power supplies just fine. Where you 'need' the extra power is if you starting hanging power hungry devices off of it (HDD usb drives for example). Otherwise the PI5 should work just fine. I really like my RPI5s as they got most everything right. Big leap over the the RPI4s.

Also I was thinking of an eink...

If you-tubing (or any video source) stay away from e-ink. Very slow refresh rates. Stick with one of those small hdmi portable laptop monitors for less power consumption.

You've been told already, pi 4 or pi 5.

That said, get the pi 5 because it's certainly worth the difference. I'm a hardware guy, and in that area it's 2.4GHz (pi 5) vs 1.8GHz (pi 4) and the throughput of the board is much better. This lessens the slowdown when you ask it to work hard. Zoom takes nearly 2 minutes to start on the pi 4, for instance. A-76 cpu cores also work better together than the A-72s in the Pi 4. They say the graphics is improved also. Personally, I'll wait & see on that one.