To be quite honest there never really was a true priority macro.
They are very similar to a what we have now. The only true difference is you could almost guarantee one ability to fire off on cooldown.
i used to use a very simple macro for my Ret Paladin.
It was your typical priority que macro.
But after playing with it for almost 2 years i can you that it was not doing what i wanted it to 20% of the time.
They only thing that would work nearly perfectly was the last line /cast hammer of wrath.
Now i know you can argue that you could prioritize the abilities to fire off more reliably in the priority you wanted, and i will admit that did happen on a limited basis.
But i can tell you now that it is more important where you put you abilities more so than anything else. You have to remember that even the so called priority macro still was firing off the first ability that came off CD. Put the important stuff at the top. not so important at the bottom. Its a little easier i will admit for Ret because our most important abilities are short CD, and each one that is more important is slightly longer.
For example my old “priority” macro was crusader strike, judgment, Templar’s Verdict, Exorcism, then ended with a /cast Hammer of wrath.
Now what i did to replicate that, without using Gnome Sequencer, is just rebinding my keys, and then using my macro function in my Naga to hit those keys in that order over and over. Some one here suggested this a few times here but most people like the huge all in one macro, which is not practical with this method.
So here is what i did, opened my Naga program, and made a new macro. just using f8 - f12
it will press the f8 then the f9 then f10 ect, and skip past if no abilities are on cd that are on that bind, then resets back to 8 and repeats infinitely. On my Naga side button 1 is target/startattack macro, 2 is always single target, 3 maintenance or procs, 4 is bust macro and 5 is AOE.
So i set side button 2 on my Naga with this macro, and set it to repeat as long as i am holding it down. Same with my 5 button for AOE rotation.
Then i went into my wow keybinds and used the right action bar1 and set f8 to 8 and so on and so forth up to f12 on the 12. They are just quick bag slots binds that i never use anyway. Now i drag and drop my abilities i want into those slots, prioritizing slot 8 as most important and 12 as least. So HOW is in slot 1 and Exo is in slot 12, Always found that TV works best in the 3rd slot from the top.
I repeated this for my AOE just using f3-f7 and binding then in simmilar fashion to the right action bar.
Now one thin i did in addition is i made macros for all my abilities, making them all with HOW as a option in the macro, and DS in the AOE version. Same thing that the old swap action bar macros would do, so even if the ability is on CD my most important ability always has the chance to fire by being there.
Edit
I just wanted to give the macro and here it is.
/castsequence reset=0.3 Crusader Strike
/cast !hammer of wrath
I repeat that for all my abilities, adding the /cast under it.
The reason why it works is because if i press a button with that crusader strike macro it will first use the crusader strike, then nothing else, it will go on CD for 4 seconds and hammer of wrath will fire next after the CD for CS is up, its how they broke chaining multiple lined macros, like the “priority” ones.
So as the macro progresses thru the 2nd time, it will fire HOW and not cause CS to go on cd. So to summarize the /castsequence line will trigger the abilities CD and lockout any additional lines in the macro until that CD is up. But the the 2nd line does not cause a CD lockout to line above it.
Like i said if you can come up with some other ideas if you go back and search this site for older Swap Action Bar macros, that were being used before GS was developed. I have a feeling GS is really just doing what i am doing manually with out all the other added stuff.