Why did they recommend the Taichi Lite specifically?It was the one recommended here (I had not heard of it) was advised to wait (which I have been doing to get AMD Ryzen 9 9900 ) and pair it with Taichi Lite
I do not know enough to judge Motherboard choices.
Maybe something like ASUS AMD ROG STRIX B650E-E GAMING WIFI AM5 DDR5 ATX or steeping up in price to Asus ROG Strix X670E-E (as high as I would consider going)
Simple Q ... will an EATX case take ATX boards .... or do I need to match ATX to ATX
You would normally buy a motherboard like the B650E-E or X670E-E only if you need 4x M.2 slots.
What features do you need?
E.g.
PCI-E 4.0 or PCI-E 5.0.
Number of M.2 slots.
Number of SATA ports.
Number of secondary PCI-E slots (e.g. for sound card).
Sound quality and number of jacks.
SPDIF / Optical.
Number and speed of USB ports on the rear I/O (including Type-C).
Number and speed of USB ports to the front (including Type-C).
Number of LAN ports & their speed.
WIFI.