The first OVA series of Urotsukidoji probably got a lot of budget, considering the quality of animation, music and direction. And it was made in the 80s, when a lot of cash was flowing into the animation business. Later on, I guess Kite and Mezzo Forte got probably higher budget than the mass. These 3 titles are kinda crossing over the mainstream, as you can remove the sex scenes and still have a proper story.
I have no idea of the actual budget spent in any of them.
Man oh man is Urotsukidoji rather bizarre. LA Blue Girl is another one that I think is in a similar category. Those 4 are also some of the few with proper IMDb pages which probably supports your thinking. Cool Devices and especially Cream Lemon are some older ones that are also pretty famous. Cool devices has 10 episodes and Cream Lemon has about infinity and the fact that they're all above average quality makes me wonder if they didn't have a higher budget. I would also throw out Words Worth and Bible Black due to long-runnedness. Bible Black: Origins is also the only hentai that has a budget (est. $60,000) listed on IMBd so it might win default.
As for more recent stuff I would guess Shoujo Sect but I don't have any good reasoning behind it. Also, Tony Taka stuff, i.e. Shinshou Genmukan; Sora no Iro, Mizu no Iro; and especially Tony's Heroine Series: Kanojo wa Hanayome Kouhosei? Cinderella Collection. The production values are really high and there's a way above average amount of voice actors for them listed on aniDB. Plus I'm pretty sure T2 is the most and/or only well known hentai artist, at the very least I'm pretty certain he's the only one with a series named after him.
Well, I doubt any of these is really what the OP is looking for but I think Shinshou Genmukan may be the closest so that's what I would recommend. Feel free to skip the prequel (it's just called Genmukan), but you might want to read the plot summary on aniDB or something. Most of the older ones look more gritty or something whereas T2's stuff looks super polished. I wouldn't say they are poorly animated (I think Kite's animation is among the best in any anime not just hentai), but it's a different kind of style and it doesn't seem like that's really what you're looking for.