Get the AC Pro or AC Lite then.
As someone who has ordered HDs (I'm hoping after being let down by my suppliers a couple of times they finally arrive on the 19th) to replace LRs I'm going to disagree.
All the previous access point models in the AP-AC range had weaknesses. Pro was theoretically fastest and could handle more clients but LR was better with listening for mobile devices and Lite was cheapest but needed 24v Passive PoE and was compromised on speed.
The HD has better transmission and reception antennae, a higher transmission power and a more sophisticated method for handling simultaneous connections. Other than the cost there is no downside to specifying the HD over any other model in the Unifi range. If cost isn't an issue then the HD is clearly the way to go.
I specified LRs previously because of the better receive antenna sensitivity but the HD is better again with handheld devices. The HDs are expensive, but for most people the biggest frustration with WiFi is the inability to connect followed by the perception that a connection is slow. Our current dashboard shows 24 mobile devices and 38 wired connections. A BT HomeHub 6 was handling it all with a 48 port TP-Link switch but everyone says the Unifi system is faster and we're able to have multiple people on EE WiFi Calling all with perfect signal quality. To give you an example of how the LRs have altered people's expectations, someone was walking here and complained that they were unable to pick up the WiFi until they were physically able to see the building, roughly 500m away. 500m! When I pointed out that most people would be happy to get WiFi when they came into the building, I was met with "But this is
proper WiFi". People's expectations shift with each improvement in what they have.
Whether the HD will be appreciably better than the LRs is anyone's guess but as the notional IT support person in the building I will be able to look people in the eye and say we have the best equipment available.