I know this may be petty, but the graphics in V turn me off. I know it was the early 3D era, so a lot of games from that time look ugly, but (IMO) KQ8 looked ten times better. Also, the controls feel awkward in that game, so it's a game I am ashamed to say I've never really taken the time to play.
I personally think it's highly possible for well-drawn 2D graphics to look much better than halfhearted 3D graphics. A game like Quake, for all its innovation, is an absolute eyesore to look at today, but back when it came out, it was like magic, which is why it overshadowed Duke Nukem 3D, which I personally think looked better than Quake did. Games that come out today with 2D graphics are usually so stylized and retro-looking that people give them a pass (see any given Mega Man game), whereas current games with 3D graphics are held up to such an insane standard that nobody is impressed by anything anymore. The first Doom game looked awesome when it came out, but of course it got overshadowed by other games with more advanced graphics, even though most of the followup games were lower quality. Meanwhile, Doom 2016 is considered to be one of the best looking games in years, but it too will eventually get overshadowed in time.
I think, if nothing else, KQ7's backgrounds were the most well-drawn in the entire original canon. KQ5 would be a close runner-up in that category. Although I'm not a fan of cel shading, it fits TOG's KQ pretty well, and the backgrounds look very good. Of the fanmade games that have come out so far, KQ3 Redux is by far the most beautiful, with KQ2+ in second place. TSL has gorgeously-animated pre-rendered cutscenes, but the in-game cutscenes tend to be stiff and lifeless. Episode 4 has an egregious tendency to swing back and forth from one to the other. Graham's interactions with the Winged One painter are pretty painful to watch since the latter has only one speaking animation, which is gesturing accusingly at Graham. On the other hand, the dream sequence at the end is amazing...provided your computer is strong enough to handle it and it doesn't just chop all over the place, like what happened to me my first time playing.
And while we're still on the topic of favorite non-KQ Sierra games, I too loved the hell out of QFG4. Visually, it's held up much better than any other QFG game.