Windows: Over-commercialization (account requirement, OneDrive upsells, ads in Start menu, Copilots everywhere). Runner up: bad performance.

Linux: Absence of a strong, universally recommendable distro. Ubuntu pushes Snap which has all kinds of problems. Fedora doesn't include proprietary drivers, causing problems with GPUs. PopOS is in the middle of switching DEs. Arch is Arch.

macOS: Liquid glass.

Windows (11 Pro): Bloat. Unusable Windows Content Search (on my 20T+ of data). Patches that cause reboots unexpectedly. Hard to configure full disk encryption that requires a password at boot time to unlock. Hard to figure out how to fix things that break, but Gemini helps. Hard to migrate to entirely new computer without a full reinstall. Touchy iSCSI support.

Linux (Ubuntu 24.04 LTS): No good integration with OneDrive and Google Drive at the filesystem level like on Windows. Too many distributions to consider. SNAP on Ubuntu (uninstalled). Scary Ubuntu LTS upgrades. Have not figured out Wine for the few Windows apps I would like to use. (Would love just having a VM like in the old days, with window manager integration.) Audio drivers, latency and music software is very fiddly. Bluetooth is sketchy, especially for audio. Support for hardware lags Windows heavily (e.g. Strix Halo, nVidia). Poor support for business devices like some scanners etc. So many problems with Wayland, screen sharing, window positioning, etc.

But I am starting a migration to Linux slowly but surely. Windows keeps getting worse; Linux is improving. (Linux user since 1992.)