not necessicarily a specific setting so much as fixing wrongs like the ranger & chopping off some of FR's setting baseline boundaries inflicted on classes to allow other settings to be less jarring & in need of homebrewing to fit.
I seem to gravitate towards running godless or weak gods settings and often make divine casters very rare so having reduced niche protection by power source is helpful. This was something 4E did well by allowing different "power sources" and "roles." (I'm not necessarily saying their layout was the right one, just that the logic is useful; 4E had a lot of useful conceptual thinking, regardless of what one thinks of its execution.)
I don't know that one needs to totally grid out a party like that, but it helps to think of roles in the party in both game design and when building a party and thinking also about the society at large, assuming you care about world building, which I very much like to tie into the classes. For example, in my Desert of Desolation game, the area was cursed and abandoned by the gods; divine casters are common in the original modules (which date to 1E) but felt wrong. So I borrowed some from al Qadim
(excellent source material!) and made the faith of many of the tribes to be the Lawgiver, an unnamed sage from centuries ago only known to be a woman, who was explicitly not divine---indeed, much of the Law is specifically guiding followers away from gods, most of which are evil and nasty. Part of the overall story also talks of "the pharaohs and their wives" so I decided that secular power was in the hands of the pharaohs (men) and the lore was kept by the wives (women). Thus the sheik is a man while the spiritual leader of the community is a woman and typical classes would be fighter and bard, respectively. (This is world design, it doesn't really affect PCs.)
So, long story short, expanding the spell lists and making sure there are multiple ways for roles to be met is IMO a good idea. I very much like the warlock invocations, for instance. The Booklock invocations really help open that path up as a healer type character, especially for a Celestial Booklock, that really doesn't feel like a warmed over cleric.