My advice would be: think about what expansion, connectivity, and upgrade options you're likely to want/need, and make the decision based on that.
There's no point in spending more for features you won't use. A low-end B650 motherboard like a Gigabyte B650 Eagle AX would be more than enough for most gamers with a Ryzen 7 9800X3D. Most of ASUS's entry-level AM5 motherboards suck, but they have some decent midrange options like the TUF GAMING B650M-PLUS WIFI, which is an especially good option for micro-ATX PCs. The ASRock B650M-HDV/M.2 is generally regarded as the best low-end B650 motherboard, is what I would personally choose, and may be worth considering if you're looking for a cheaper micro-ATX option or if (like me) you just don't need a ton of connectivity. I would recommend against getting anything worse than that, including similarly-priced ASUS or Gigabyte motherboards. Gigabyte and ASUS' entry-level motherboards generally aren't as good as ASRock's this generation (in previous generations, ASRock's HDV motherboards were god-awful, but ASRock has apparently finally realised that making the unambiguously-worst motherboards on the market was damaging their reputation).
If you want to overclock, especially if you're likely to want to upgrade to a significantly more powerful CPU in the future, you should get a motherboard with a better Voltage Regulator Module (VRM). The Gigabyte B650 Aorus Elite AX is a great option if you're looking for a significant VRM improvement compared to the low-end AM5 motherboards, without being a lot more expensive. For some reason, the B650 Aorus Elite AX actually has a better VRM than its B650E counterpart, with a 14-phase 70A VCore compared only 12-phase 60A on the B650E. If you're really serious about overclocking, X870/X670E/X870E ROG Strix/Crosshair and Aorus Pro/Master boards might be worth considering, but these would be a waste of money for most people.
If you want more USB ports, more PCIe slots, more M.2 and PCIe slots with PCIe 5.0, more SATA ports, more RGB headers, USB4 support, or any other features that are only available on more expensive motherboards, then don't be afraid to spend more for those features, just be aware that the more different requirements you have, the harder it will be to find a motherboard that will meet your needs for a reasonable price. The ASRock B650 Steel Legend WiFi (which is actually a B650E motherboard, but is named differently to distinguish it from the B650E Steel Legend WiFi, which is a different motherboard with a better VRM but worse connectivity; ASRock's naming is incredibly dumb, even if the board is good) is usually the cheapest AM5 motherboard with PCIe 5.0 for both its top PCIe x16 slot and its top M.2 slot. If you want to stick with ASUS and Gigabyte, the ASUS ROG Strix B650E-F Gaming WiFi and Gigabyte X870 Eagle WiFi7 are both good options for PCIe 5.0 connectivity (and also USB4, in the case of the X870).
