When there are many players to target, for example during a fate, it can take a long time to cycle through all the PC's to heal the tank or other player in need of a heal. I imagine this will difficult in 24 man raids as well.

I use a controller 90% of the time but I hear it's also difficult to click the desired target with a mouse when there are many targets on screen.

Is there a way to target the player with lowest HP (within range) immediately?

If not I suggest to the devs that target PC with lowest HP should be keybindable and macroable (to cater to both mouse/keyboard and gamepad users). Ideally we could modify this to choose next lowest so you can repeatedly press to cycle from lowest hp to highest hp player (to avoid everyone healing same target and also to allow you to target the next PC to heal while you are casting the current heal).

To me a macro such as this would be my holy grail for healing in large groups:

/targetlowHP
/action cure <t>

You could just keep pressing it and automatically heal players in the order of priority. If a squishy gets hit you may want to skip the tank even if he has technically lower HP, so something like /targetnextlowHP to skip to the next lowest would be great.

Another idea to extend this further is a setting or text command to permanently switch the tab (dpad) target cycle order based on either distance, lowest HP (for allies), maximum HP (for enemy from small fry to boss), enmity, etc.