Leather is more breathable than pleather, but still will warm up the ears. Alcantara is probably best you can do for pad material on a closed/semi-closed headphone for comfort with good quality sound. Trying out the Yaxi Alcantara and leather TH pads and really liking them, do prefer the leather to the Alcantara for sound. Of all the pads I've tried with the TH-X00 Purplehearts, my favorites have been the ZMF Ori Lambskins, Yaxi Lambskins, and Jmoney V3 lambskins (no other pad sounds like the Jmoney V3... been looking for an available alternate for years with no success.)
Not really a fan of Dekoni pads as they are not comfortable for me and sound worse compared to most other pads I've tried - simply too muffled/boomy and flat sounding. Stock, worn out Denon AH-D2000 pads are better to me than any Dekoni I've tried.