One system you’ve forgotten is Rocker style dropouts. They’re a nice solution for bikes with relatively open CS/SS angle. Maybe not as suitable for a DJ or SSMTB but still a good one to have on the list.
Of the systems listed I’ve ridden a good few thousand kilometres on Horizontal Dropouts (Track Ends) with a 135mm bolt on hub, Paragon Sliders with a boost thru axle hub and Taiwanese Rockers with a thru axle hub. I’ve never used a EBB and to be honest I’m not that interested. I have enough trouble with creaking bottom brakets as it is haha.
I think the Paragon sliders are my favourite for trail use. So simple to setup and take your wheel in/out which i find I do a lot more of on a MTB. The only issue I had was some slipping/creaking but proper bolts and a good clean and degrease of the inserts fixed that. One thing to note is that sliders aren’t ideal for rack mounts but that doesn’t seem to be a priority for you.So yeah I’d put them on the MTB.
On the DJ rig I think you should keep it simple with something like the BFS “Fish head” dropouts or maybe get creative and make something yourself like @Pi_bikes suggested. If you want to go slightly fancier but still use a bolt on but then Bear Frame Supplies (also BFS 
) make a nice horizontal dropout with an inbuilt adjuster. Kinda reminiscent of the track ends PAUL used to make.
Oh and one last alternative tensioning hack that might be a bit cleaner than a deraillier mounted tensioner is to use an ISCG mounted chain guide. Could also be pretty neat on a DJ rig if you ask me.
