I get better results using micro sprayers over drip emitters.
Correct, if you are using drip emitters, its useless to put them on top of mulch as it wont get coverage. for top of mulch, micro sprayers is needed.
I have been using above drip "Micro sprayer" system for over 3 years, but I am now started converting to another system using "1/4 inch "Dripline" tubing, where the emitters are built-in inside the tubing.
The drip Micro sprayers have been giving me good coverage, but the problem I am having is the repeated flow adjustments that I need to do from time to time. I notice that the sprays diminish after few weeks/months or so, and I still have no idea what causing it! Occasionally, the sprayer's top come loose too, and there goes the small water fountain going straight up in the air...So, to me, this "Micro sprayer" while serving the purpose, but frequent checking and upkeep is required...
The "Dripline" system:
The "Dripline" system so far have not been giving any trouble for the last 2 years that I am using it; and I found that installation and future expansion (when trees grow bigger) seems to be simpler for me (no need to run another line) and possibly more economical as well. I also installed a 1/4" one way valve prior to inserting the Dripline, for full flow control.
Oh, by the way, I had run this Dripline on top, thru or below mulch, without any issue so far.
Just sharing my own experience...