All six options are good devices. The question is which one matches what you're actually going to use it for. Here's the decision tree we use when friends ask.
If you're buying primarily for meetings and note-taking
Get the ReMarkable Paper Pro Bundle if budget allows ($629). The 11.8" canvas is the only one that actually replaces a legal pad without feeling cramped, the 12ms writing latency is the only specification definitively below the human-perception threshold, and the included Wacom Marker Plus pen is genuinely the best stylus on any e-ink tablet. If $629 is out of range, get the Kindle Scribe 64GB ($430-500) — the on-device AI handwriting summarization is the killer feature that turns weeks-old meeting notes into searchable summaries.
If you're buying for reading + occasional note-taking
The Kindle Scribe (16GB or 64GB) is the obvious pick if you have an existing Kindle library. The ecosystem integration (Send to Kindle PDF workflow, Audible audiobook bluetooth pairing, Whispersync across devices) is the value proposition — no other tablet has this. Get the 16GB tier ($340-430) unless you specifically know you're loading a large PDF library, in which case the 64GB ($430-500) is worth the upgrade.
If you refuse to be locked into one ecosystem
The BOOX Note Air 5 C ($469-499) is your only option. Full Android with Google Play means you can run Notion, Evernote, OneNote, Drive, AND the Kindle app on the same device — and add color PDF annotation on top. The trade-off is Android complexity (more menus, more settings, more potential for software friction) vs the elegance of ReMarkable's walled garden. If you're comfortable managing Android, this is the most powerful tablet in the lineup.
If portability matters above all else
The BOOX Tablet Go 7 at 195g (vs the 410g Note Air 5 C, 489g Kindle Scribe, 525g ReMarkable Paper Pro) is the only e-ink tablet that's genuinely one-handed-portable. The 7" canvas is constraining for serious meeting notes but perfect for transit reading, lecture notes, journaling, and quick capture. Get the B&W version ($229-259) for novel reading; get the Color version ($249-279) only if you specifically want manga, comics, or magazines on a portable device.
If you're a designer or sketch artist
The ReMarkable Paper Pro Bundle is the only credible option for serious sketching. The 11.8" canvas is large enough for actual creative work, the Wacom EMR pen has 4096 pressure sensitivity and tilt detection, and the textured display surface delivers real pencil-on-paper friction. Anyone telling you a Kindle Scribe or BOOX is comparable for sketching hasn't actually drawn on all three.