Hi there,
And Welcome here…
So the C6 has been out for a good while, I use them all, and feel the S3 is the only one worth using IMO on mission critical projects. It’s the only DUAL core too. The C5 is just another permutation of the single core variants with an Added 5Ghz WiFi… is the juice worth the squeeze ?
The Package size released by the manufacture determines allot of how fast or if at all shoe-horned into the Xiao Tiny size.
Package Sizes
The package sizes of the ESP32 chips also vary. The ESP32-C2 is the smallest, with a 4 mm x 4 mm package, while other ESP32-C series chips, including the ESP32-H2, come in 5 mm x 5 mm sizes. The ESP32-S series is slightly larger, measuring 7 mm x 7 mm, which accommodates additional GPIO pins and features.
for anyone looking here is a loose chart from the link below if you want more info.
https://www.espboards.dev/blog/esp32-soc-options/
HTH
GL 
PJ 
I’m in the S3 camp ALL-IN … most available performance, most compatible with older code base, Good enough Deep Sleep. Most GPIO’s Available with the B2B connector Which opens up a Veritable horn of Plenty it is a virtual cornucopia of options 