would you suggest Shimano or something like Superstar / Uberbike?
I dallied with after market pads… and to be honest found them hit and miss.
I had one pair (planet X) that just never seemed to bed in or grip properly whereas others from the same batch worked fine if not as well as the genuine ones… superstar were cheaper to buy but thinner… so wear faster….
As always there is the pay a bit more…. but at the moment the SLX M7000 are a pretty good buy… you get the reach adjustment… bite point with the right safety bit etc. you might get something £10 cheaper per end… so £50 instead of £60 for both… but if at some point you go for new calipers etc. you’ll be happy with the SLX levers (functionally as good as present XT M8000) …
http://www.chainreactioncycles.com/brake-spares/mtb-disc-brake-spares?f=4294964100
If you do change callipers remember you get a “free” set of pads… so its a good time to switch… but you would need new banjo’s for the SLX calipers