Aside from Farsight and Kais, all the others are meh. Tau victories are usually so full of bullshit its hard to take them seriously. The fact that they still exist in and of itself is bullshit, given the Imperium's galactic level military power, but thats a story for another time. But their models are wonderful, and they appeal to anime lovers, as they are the closest thing to it. Plus they are one of the few factions who care about their people aka noblebright, which appeals to people.
The things I dislike most ... In a few cases, it's the words But mostly, I'd say it's the "Marines must always win" overall generality of the things. It doesn't happen 100%, but still, in some cases it's as if Humanity actually losing, as opposed to pretend-losing, would result in loss of something dear and personal to GW high-ups. I'm trying to ease back on my vitriol here so please insert swear of choice to chosen organ of said GW person. Now don't get me wrong. I also enjoy selected bits of the HH and they have Marines aplenty. Also, I have a certain fondness for Night Lords (which does not extend to wanting them not to die). I would like a sight amendment to the good Mr Gobmaw up there @GobMaw_HellSmasha 's words in that I would say "more non-Marine stories as well as Marine ones". No, GW, you don't have to do less with your favourite boys, just do the rest as well. Number one peeve for me today aside from these is the lying. Lying you say?? Well; such things as "Here is an Exodite story! You should totally read it! Look! Exodites!" (actual email from GW, slightly paraphrased *cough*). When what they really meant was "Story with Exodites being killed by Marines". Goes with "Harlequin story!" (Harlequins being killed by Space Wolves) and "Novel called Harlequin!!" (novel not about a Harlequin but an Inquisitor, barely featuring Eldar). I'm not saying they are bad stories. I'm saying that straight up lying to me to sell them is going a bit far.
You would absolutely love the Tau then, cause they have mastered that trait far better then the Marines.
The things I dislike the MOST is the actual table top WH40k game. It feels like it follows this simple pattern 1. Is it space Marines? Go to 2 if Yes Go to 3 if no 2. Chaos or Imperium? Go to 3 if Chaos Go to 5 if Imperium 3. Give weird nerfs, and confusing Special rules 5. BUFF 4 DAYS Then again, most people play Imperium Factions anyway so GW has to make their money somehow.
Space Marines are balanced, they arn't even remotely broken like Eldar or Tau can be. In fact I've seen more Tau then I have Spacemarines in my store when I used to play. As for Chaos...I agree it's not in a good way, but everyone pretty much can guess Chaos is in for a major rework soon.
The first part is pretty much exact opposite for me. Whenever I go to my GW store, its Space Marines Galore, seconded only by Necrons.
View: https://www.youtube.com/watch?v=mfH814a-J70 sums up my thoughts I guess oh and too many space marine books, skreew doez goiz
I should correct myself, Everyone at my store had a SM army, it's just that everyone used Tau to win.
I use 40k novels as a break from my school reading, but I mostly read HH stuff. I think I dislike the aversion to actual plot sometimes. Sure there's movement, but it's usually just another way to get to fighting. Or the movement is nowhere near as energetic as the fight scenes. McNeil's early stuff in the HH is great. I also really love the Night Lords trilogy. I think I also take issue with novels taking themselves as very serious but not 40k serious. 40k goes over the top and is almost humerous. Sometimes it's so damn crazy it is funny. Angel Exterminatus has some moments like that. Some novels treat the setting very seriously but neglect the plot for action. I also really hate how trans-human and post-human are misused and used interchangeably.