Everyone seems to like Nova launcher a whole lot. I had it on an old Samsung Epic 4G phone and I, too, liked it quite a lot. I haven't tried it on the Tab S 10.5 yet, but I probably will eventually, just for kicks. I also very much like Solo launcher, which I have on my G'Nexus 5 phone -- excellent customization options, change icon sets, lets you fully control the aesthetics of most everything, and has quite a lot of other nifty bits, and it's super smooth and fast fast fast, and it doesn't eat much battery or storage space; and it's free, and it's ad-free! But on the Tab S, for some reason, the Solo launcher is not ideal -- for one thing, it makes the icons in the apps drawer look too small. But it really is an excellent launcher, and I'd suggest you try it, and try Nova, and you'll probably like one or both of them a whole lot.