Hi Jaz
I think zebs need wood in the tank like most people have.
There are 3 factors I look for in wood and that it easy to keep clean,places for zebs to hide and good to the eye for me it is a easy choice of the 3 woods and I would choose No1 Mangrove wood (mine comes from peat bogs I think in this country)so is called bogwood.
The Mopani wood does not look natural to me and I dislike it.
The twiggy Red moor wood no hiding properties and hard to keep clean by that I mean scrubbing it.
Mangrove wood will make your water brown for a time but will go with water changes .
I think all three woods will sort of grow a (white) film slime over them when new to the tank but more so the Red moor wood IMO,tends to have more sap in it.
Its down to what you like best and other caves and places for zebs to hide as to how much wood  
 
I only have 2 bits of wood in my adult tank and 4 fish 4 caves and few bits of rock and this works well for my zebs .
Hope this helps .
Jerry
 
			
			
									
						
							Caution is a most valuable asset in fish keeping, especially if you are the fish.