If we allow for a fair amount of childish stupidity
>lists some of my fave anime ever
fuck you man your opinion sucks
i didn't find any of those to have any real childish stupidity
ok maybe Sakurasou but that also had plenty of fan service
i see childish stupidity as like, Pokemon or maybe Yo-kai Watch or other shows which are just super cheesy and too childish/light-hearted such that it's actually kind of cringeworthy
Assassination Classroom is a comedy and has some silly jokes but it's not the kind of cringeworthy material we get from watching a show aimed at people less than 10 years old
anyway Blue Leafeon, I think I'm pretty good at suggesting anime, but it's hard when you say what you're not looking for as opposed to what you are looking for.
Here are some though:
Haikyuu!!: Sports anime, volleyball. I didn't care for either of those before watching this anime, and came out an ultra mega fan. However, I am also a real-life athlete who loves the adrenaline and competitive nature of sports, so YMMV.
Aldnoah.Zero: It's a little dark but compared to Code Geass or Attack on Titan or Tokyo Ghoul or other stuff (there are things even darker than those ofc, those are just big names), it's really not that bad. There's occasionally some blood and brutal character deaths but if you can handle it, there's not much fan service or childish stupidity (at most, a character acts childish, lol). That aside, it's a fantasy/mech show.
Buddy Complex: Another mech/war show, this one with time travel. Not that dark, even less than Aldnoah.Zero IIRC, maybe a tiiiny bit of fan service but I don't remember any (there's just a bit of romance).
Gatchaman Crowds: Going down MAL, skipped from "B" to "G", lol... too many dark shows I've watched... this one isn't dark IMO so much as it is very deep and like... psychological/sociological (as in it covers psychology and ESPECIALLY sociology and if you pay attention and think it will like, really get you thinking with how deep it is). There's no real fan service or childishness IIRC.
Gekkan Shoujo Nozaki-kun: Has a bit of fan service maybe but it's mostly a comedy with a bit of romance. Tbh I don't remember any fan service if there was any. I suppose it might come off as stupid sometimes but not in a aimed-at-5-year-olds way.
Isshuukan Friends: Touching show, I guess it'd be something like... romance/slice of life? Eh. For basically any of these anime you can see the MAL page for some quick info (just don't read the reviews ) http://myanimelist.n...shuukan_Friends
I might recommend Log Horizon but it has a bit of fan service. Probably a bit less than SAO but eh. I'll stay on the safe side and not recommend them I guess.
Noragami is probably a bit too dark...
One Piece is great but can be dark, stupid, and have fan service, depending on what's going on
One Punch Man, if you haven't heard/seen it already
Rokka no Yuusha is a little dark and has a bit of fan service but isn't bad or gratuitous on either IMO.
Rolling Girls is solid but has a lot of female characters. I wouldn't really call it a fan servicey show, it's just super colorful and bright and has some cute female characters. there may have been a fan-servicey scene or two but I don't remember them as that's not what the show is about.
Samurai Champloo is a classic but too dark so RIP
OH! Tsuritama is a show about fishing that is like, way better than a show about fishing has a right to be, XD. But seriously it's pretty good, got good character development and comedy and such. No fan service or childishness or darkness IIRC.
Working!! and Oregairu have some light fan service (no like nude stuff, but they are about romance so you'll see characters blushing or the like), but they're mostly comedy and... slice of life, I guess. Working!! takes place in a restaurant, which is a little refreshing. Oregairu takes place in a school/on trips, but it's a parody of the romantic comedy genre and can get pretty insightful/deep at times. (I really liked both Working!! and Oregairu, giving them 9's and 10's)
I think that's more than enough so I'll stop there.
FWIW I did not mention anything with any real fan service IMO, a little bit is kind of a given since it's anime and all but the worst I remember is one scene where they're naked (but no tits or the like) in Aldnoah.Zero and even in that case it's very serious in the sense a real incident takes place there so it's not just unnecessarily watching someone shower only for them to come out of it looking wet and sexy or w/e
there are some naturally just sexy outfits and such but again. None of these shows are ecchi or shows that make their name on fan service, or I wouldn't recommend them. I think every show I listed is at least an 8 if not higher except AZ season 1 so yeah.