My main UI has a number of criteria. For my information needs I use FuBar (ace) with a significant number of plug-ins (you can probably guess what most of them are from the screenshot).

In combat I want to be able to use the keyboard for most combat tasks. While I used to use Bongos to replace the standard action bars I'm now using Bartender3 since it is an ACE2 addon. Both allow lots of bars and are easily configurable to size, location and hot-keys.

After getting tired of dying because I didn't look at my health bar in the upper left corner of the screen I downloaded a few HUD interfaces. I am now using ArcHUD (ace) and LOVE it.

After starting to use Steady Shot a lot I finally understood why it is nice tto have a cast bar for autoshot (so that you can start your steadyshot right after you fire off your autoshot). For that I use LittleTrouble (ace).

For "smarter" keys I'm using a few different solutions. AutoBar allows me to keep a small bars with buttons for "best food", "best drink" etc. The buttons are updated automatically depending on what is in my inventory.

I use now use my own macro to get access to call/dismiss/revive and mend pet (and use Autobar to feed):

/cast [target=pet,dead] Revive Pet; [modifier:alt, nopet] Revive Pet; [modifier:alt, pet] Dismiss Pet;[nopet] Call Pet; Mend Pet

Another critical aspect for me as a hunter is good feedback on the range to my target (even more so now that I can't have my action bar switch based on the range). There are at least three different mods that will give you a range estimate. Since I like Zanzer's work for other things (and because it seems to get it right) I am using ZRangeCheck.

Finally I use Chronometer (ace) to help me know when to set a new trap, fire another sting etc.