Latency is exactly why I'd prefer a last-gen radio with open-source drivers. An 802.11ac router with the latest open-source drivers (ath10k and mt76) will give you better real-world latency, because there are open-source developers working to optimize for the metrics that actually improve real-world user experiences rather than seeking the largest achievable throughput numbers on naive speed tests.

802.11ax on its own does nothing to address the problem of wasting too much airtime serving a client at the extreme edge of your AP's range where neither 802.11ax or ac transmission rates will work. That kind of problem must be tackled with better QoS strategies that are not inherently tied to any particular generation of the WiFi standards, but in practice can only be developed and tested for chipsets that are sufficiently hackable