Start with a budget of course. How much do you have to spend on the total system? Or just the motherboard?
Number of USB ports is pretty straight forward. If you are just Keyboard/Mouse, then two. All boards have at least two. So start looking at other things you plug in. USB external drives like flash drives, your phone for charging or downloading pictures, joystick/steering wheel/controller, USB headset. What type of connectors USB A, or USB Type - C? Do you need USB4 speeds, USB 3.2 1x1 enough, or do you have anything that needs more performance. Thunderbolt?
PCIe slots: For a gaming system, you certainly want a discrete GPU. So at least one x16 slot. All boards tend to have this. Then we come down to add in cards. Do you have need for network speeds beyond 2.5Gbps (There will be boards with 5Gbps and 10Gbps built-in, or you can plug in a network card into an available 4x/x16 slot. Do you need WiFi, again, some boards will have that built in, or you can add a discrete card. Other devices might be additional storage slots for M.2 drives or disk controllers for SATA or SAS drives if the motherboard doesn't meet your needs out of the box. 2-8 SATA ports is possible on motherboards, but bandwidth may be shared between various things in the system.
Onboard motherboard audio is pretty decent these days. But there is the bare minimum like 5.1 surround sound, you can pick out boards with better audio 7.1, etc. Though most enthusiasts tend towards USB DACs these days (another USB port needed)
M.2 drives. My suggestion is to get a large PCIe 4.0 NVMe drive, like 2TB. Most boards have at least two M.2 slots, and getting 2 or 4 TB drive in the future should be sufficient. But if you want all your games locally installed you need to expand that. Either through PCIe cards that split out multiple M.2 slots (which means you need a motherboard that supports complex bifurcation) or you can do SATA drives for bulk storage.
And last and certainly not least, how big of a motherboard? Mini-ITX limits you to zero expansion cards beyond the GPU, max of 2-3 M.2 slots and they will either be stacked or on the back of the motherboard. Micro ATX generally have a 4x and maybe a 1x slot accessible after a two slot GPU is installed, but larger GPUs cover up most of the board. Micro ATX tend to be the cheapest boards, and offer minimal features. And ATX generally have room for seven slots, but only 4-5 are generally useable with M.2 slots tucked in here and there and can be quite fully featured. There are also sizes like Full ATX, EATX that are even larger and require slightly larger chassis.
Brand isn't so important as the individual products, price ranges, and features.
If I were to make a blind recommendation, something like these:
https://pcpartpicker.com/product/sz...ifi-atx-am5-motherboard-b650-gaming-plus-wifi
https://pcpartpicker.com/product/Tz...ifi-atx-am5-motherboard-b650e-pg-riptide-wifi
https://pcpartpicker.com/product/Lw...fi-atx-am5-motherboard-mag-b650-tomahawk-wifi
https://pcpartpicker.com/product/m7...tx-am5-motherboard-x670-aorus-elite-ax-rev-10