I recently have been playing around with a few boards in this area. Besides the RPi3/4/Zero, I've got the Beaglebone Blue/Black, Jetson Nano, and Odroid-C4, with an Odroid-N2+ shipped my way yesterday.
The Raspberry Pi's have undoubtedly the widest community support, so can be great if you're a beginner. However, for a lot of projects, I've been frustrated by it. Things that should "just work" like i2c don't always, and it's limited for some tasks like hardware PWM (only two PWM outs vs. six for the Odroid). On the other hand, the Jetson Nano's ability to run CUDA is killer, especially for certain computer vision tasks, but it doesn't always seem to have great docs and the forum isn't always particularly helpful. The Beaglebones are fine, but tbh seem to be showing their age. The strength of availabile ARM SBCs has drastically scaled up even in the past few years, and I don't think they've kept up.
The Odroid-C4 board is a great middle ground. It took a little while to figure out, but if you're comfortable reading docs and asking questions on community forums (I needed to add certain GPIO groups to a config file and reboot to see them in the device tree, but you don't need to be able to compile your own kernel or anything) and not on a deadline, the performance is both better than the Pi4 on paper and seems noticably smoother for certain tasks than any of the other boards, especially basic desktop use. Also, no onboard WiFi, but USB chips have been plug-and-play so far. The N2+ has even more cores and a built-in real-time clock + coin battery holder (maybe useful for hibernation modes?), so I'm looking forward to playing around with that soon.
How is the access for various OS distros for the non-pi boards. I tried a few about 6-8 years ago that were more powerful than the Pi at the time, but suffered from a lot of misc issues, and the availability of baseline OS support was really lacking at the time. I can run Ubuntu Server images on the Pi, but how is the support on this other hardware?
I feel more comfortable that the x86 devices will be better supported by community distros than non raspberri pi arm boards from this past experience. The 8gb Pis are enough to play around with home-lab getting more familiar with Kubernetes and setup/configure for distributed software, but wouldn't mind a bit more compute power to go with it.
Also, I kind of wish more of these were direct sale rather than kickstarter/crowdsupply backed, etc. I have already lost enough money on various projects that I've stopped backing things. I know it's always a risk, but at this point it's been much less worth it for me.
edit: One addition, cases for those of us without 3D printer access or experience is another common issue.
The Armbian distro covers a lot of various boards. Before I purchased my N2+, I just made sure I had a more common/mainstream distro available, which Armbian appears to cover.
I wish there were 100%-compatible but more powerful Raspberry Pi Alternatives. So you could use the original Raspbian OS, Raspberry hats and all the GPIO and software recipes you can find around but have better I/O etc at the same time. As far as I know existing alternatives are far from being 100% compatible.
What I like about the raspi 4 is the 8GB ram version. What I like about some of the other boards is support for SSDs which is a hassle to setup on a raspi.
I was an early adopter of ARM devices and have owned more than I really should have. That said, if you really want to spend time and money on this hobby, choose performance AND long-term support.
Odroids are great devices but the community depends on a few stars who do it for love. Raspberry Pi has made progress and I must say that I like the R.Pi 400 (i.e. keyboard Pi) very much.
I bought an ODROID-HC1 to do some data recovery tasks at some point during the pandemic. I was very impressed by their polish. The hardware was quite reliable and the software stack was on par with RPI. Overall, do reccomend.
IMHO, such a question is a bit meaningless for the Pi's. The main purpose of a SBC market is to get a general purpose computer for a low price. The compute, IO, etc. performance is limited only by what you're willing to pay.
E.g. the 4Gb Jeston Nano has a lot of compute power compared to a 1Gb RPi, but the price of $99 vs ~$30 means it's not really an "alternative" as much as it's a product intended for a different purpose.
You can even get full blown x64 PCs in roughly the same size. They'll blow away any of the RPi line, but at a price.
The Raspberry Pi's have undoubtedly the widest community support, so can be great if you're a beginner. However, for a lot of projects, I've been frustrated by it. Things that should "just work" like i2c don't always, and it's limited for some tasks like hardware PWM (only two PWM outs vs. six for the Odroid). On the other hand, the Jetson Nano's ability to run CUDA is killer, especially for certain computer vision tasks, but it doesn't always seem to have great docs and the forum isn't always particularly helpful. The Beaglebones are fine, but tbh seem to be showing their age. The strength of availabile ARM SBCs has drastically scaled up even in the past few years, and I don't think they've kept up.
The Odroid-C4 board is a great middle ground. It took a little while to figure out, but if you're comfortable reading docs and asking questions on community forums (I needed to add certain GPIO groups to a config file and reboot to see them in the device tree, but you don't need to be able to compile your own kernel or anything) and not on a deadline, the performance is both better than the Pi4 on paper and seems noticably smoother for certain tasks than any of the other boards, especially basic desktop use. Also, no onboard WiFi, but USB chips have been plug-and-play so far. The N2+ has even more cores and a built-in real-time clock + coin battery holder (maybe useful for hibernation modes?), so I'm looking forward to playing around with that soon.