Nano Pi T4 $109 [1]

6-core, 64-bit, 4GB ram, EMMC, GbE, Wifi5 (AC), HDMI 2.0 (4k), USB3

Best software besides Rasberry I've seen is from these guys. Great build quality too.

1: https://www.friendlyarm.com/index.php?route=product/product&...

Beyond the OrangePI boards at the same price point as RPi, I like the UP boards which use x86 compatible chips for that $100-200+ bracket, you get good, fast, processors with decent memory options and don't have to screw about with weird android-orientated hardware.

Depends what you mean by "similar in spirit", but there are a smorgasboard of single board computers and self-contained computers out there at a multitude of different price points.

If you're looking for just a small computer, the Intel NUC is a good place to start.

Slower CPU than the Rpi4, but the Jetson Nano's GPU makes for a reasonable desktop experience. $99

Also, a refurb Asus Chromebox would be around $150 if you want x86.

Software support (up to date distro, timely security parches to kernel, reasonably unbuggy drivers et ) is usually the weak point of arm boards. Even raspbian traditionally lags a bit there but most other boards are worse. You are probably better off with low end x86.

I really like Hardkernel's Odroid boards. They have a big catalog for many use cases and are a lot more performant than the Pi but less open hardware/driver wise and lack on board WiFi/BT. But as others have said, there are A LOT of similar boards. If you want something very small, the NanoPi boards look nice but I have never tried one of them.

Basically every Atom board ever.

How about a used lenovo m92p