If someone can find me a similarly powerful micro PC that runs a full fledged *nix OS, has a full development environment, consumes under 5W idle with a similar level of hobbyist support at a similar price point I'm all ears.
Odroid C4. Much, much better mainline/vanilla kernel support (Quad-core Cortex-A55 with Mali G31 GPU, in an Amlogic S905X3 system-on-chip, with 4 GiB of RAM) -- basically all non-vendor-tied Linux ARM distributions will work --; at least as much computational power as RPi 4; and even lower power consumption. The only issue is the price; currently $54 USD and up. 128 GiB eMMC module does add USD $45 to the price, too.
Most importantly, Amlogic (
Meson), Samsung, and Rockchip SOCs do not have the hardware issues with silently dropped USB packets that all Raspberry Pi hardware suffers from (albeit semi-successfully worked around in their software).
While the
forums aren't as active as Raspberry Pis, they're helpful, and especially
do warmly welcome any open-source information (and even ask permission, then include in their guides and documentation -- have personal experience on this) if useful for other users too.
I don't own a C4 yet myself, but do have a C1+ and HC1 (NAS version of XU4), and at least had a C2 but it might have gotten lost at some point (plus half a dozen of other SBCs, like one La Frite; can't even remember all of them right now), but it is at the top of my list of desirable SBCs I'd like to buy and develop on.
Rockchip RK3328 from Olimex is near the top, too; with
Sinovoip Banana Pi R64 at the top of my Linux-SBC-router list, right now. (My current router project uses
Mikrotik RBM33G using OpenWRT toolchain and kernels.) I included this so that you can see the sector/direction of my interests, and base your estimate on how useful my opinion might be for you, based on these; others' valid opinions do vary a lot here.
Edited: I do think the RPi foundation made a huge difference in the Linux SBC market, especially pricing-wise: they brought SBCs to hobbyist price ranges. SBCs existed well before, especially in the automotive environment (anyone else remember when PicoPSU with its ATX power connector came to market? To be used with micro-ATX automotive PCs?). The camera interface was a stroke of genius on the original RPi, too; that's what got me to buy one. I just think their community is toxic, leadership is evil (especially towards the open source projects their products rely on), and advanced users should migrate to more reliable, better supported hardware, that is not dependent on a single vendor or vendor-provided software at all.