@Lynx and I will continue the RT3200 WDS discussion elsewhere, no problem. But @Lynx and @slh have both raised excellent points here that many others in the community will surely find beneficial when considering the mesh vs WDS options.
In the spirit of answering your questions (almost feels like you use bold type to "shout" stuff, which isn't cool):
I have tried wifi mesh, specifically 802.11s with and without batman-adv and found it to be extremely underwhelming on the hardware I tested it on.
So to be completely fair, you asked an extremely generic question to begin with and you're going to get a broad range of answers. If you aren't interested in feedback from RT3200 users, you should update your question to a more specific, "Who tried wifi-mesh on hardware XYZ?" On RT3200 hardware at the time of writing this, I would say "No, it does not work well." An Archer C7 or Netgear R7800 user may have a completely different take on it.
1, 2, 3, 42, 834? How is anyone supposed to answer this because you gave no clue as to how much area you are trying to cover, the type of wall materials in your space, what kind of hardware you're considering, 2.4Ghz vs 5Ghz vs 6Ghz, etc, etc.
Generically speaking a "mesh" would consist of 2...N nodes. The basic concept of mesh technology is that it dynamically configures routes between nodes and recalculates as you add/remove more.
I've also tried mesh on Openwrt with and without batman-adv.
I initially had it set up between two routers using 802.11s, one in a shed/workshop to connect to an outdoor IP camera, because its built in wifi kept dropping out.
Not using mesh currently, but I eventually got it working with Batman-adv and setup for both 2.4ghz and 5ghz, so that the router outdoors could connect to either of the two in the house which both have wired LAN connections. Reason for using this setup was neither 2.4 nor 5ghz were reliable due to multiple neighbour's access points frequently switching to whichever 2.4ghz channel I was using, and the lower range of non-dfs 5ghz channels being swamped too.
here's an iperf3: routers are bthub 5s using 802.11s with batman-adv