My issue with rap, dub or hip-hop is the anger. I also recognize the anger is to screen out ppl like me too. It's a language in itself. I have found a few that I can follow, sometimes I have to look up the lyrics though (a PITA). I like it when it's more musical; M.I.A., The Streets, Arrested Development, Faithless, Tricky, Chemical Brothers, Asian Dub, even some Emienm. It's just stuff I run across. I'm not familar with it enough to tell the difference between the styles, just if I like it or not.
I enjoy hip hop a lot. My favorite music genres are Classic Rock and Funk, but Hip Hop is up there. I used to be into much more than I am currently, but then again I was more into new music years ago compared to now. Though I did like Lorde's pop hit "Royals" so I'm not completely out of the game.
What I think most people don't like in rap is the gangsta stuff, but that's just the genre going hardcore when it was finally at level of being accepted as legitimate art form. Back in Run DMC days and Beastie Boys, circa mid 1980's, everyone outside of rap was thinking it was just a fad, kinda like grunge in the early 90's.
Interestingly of the artists you cited, I'm only familiar with Arrested Dev, Tricky, Chem Bros and Eminem. And other than Arrested Dev, none of those are ones I got into. My favorite was Outkast and Cee-lo, both of whom were huge in the latter part of the last decade. I was into both in the late 1990's. I could name about 20 other artists that I'd recommend to persons not so familiar with rap/hip-hop, but I realize you gotta want to get into it, otherwise it'll all sound about the same and any affection won't last long.
One of the reasons I really really like Beck though is he spanned so many genres, including hip hop/rap. Him and Prince are two artists in last 30 years that I think will be seen in same way Dylan and Elvis are seen, as musical geniuses ahead of their time.
I do actually like all genres of music, but don't like all artists in all genres. My least favorite genre would be country, but there are country artists I can either tolerate or respect, and as Beck has covered that genre, it isn't one I can rule out as unlistenable.
With all that said, my favorite artist of all time remains as Led Zeppelin.