The only major difference between WPA2 and WPA3 (from what I've read, at least) is that it essentially negotiates unique keys for each device that connects to the access point. This adds a layer of security between devices that are already connected and authenticated to your router (i.e. devices you've input your WiFi password for), such that devices can't snoop on or inject packets into communications meant for other devices over the air. WPA3 also claims to provide forward secrecy by negotiating new keys for each connection, but from my own experience looking at intercepted WPA3 handshakes I've seen implementations reuse keys a few times.
Other than that, it's pretty much just WPA2--same AES encryption, key derivation and all that. If you're looking for a router that will provide solid security guarantees, I would recommend one that can be easily flashed with OpenWRT, DD-WRT or some other open source router firmware. Attacks to do with poorly written proprietary firmware are often far more likely (and severe) than the kinds of attacks that WPA3 would mitigate. (side note--OpenWRT supports WPA3, so that's a plus).