http://www.imdb.com/title/tt2560140/par ... tt_stry_pgThere is what IMDb has to say about the content. From what I've seen of AoT, this pretty much sums up what you're in for. I think AoT is officially rated TV-MA, at least that what it says on the back of the Blu-ray/dvd case. When I seen it on Toonami it was TV-14 so idk. Either way, it is DEFINITELY way more violent then Death Note, which is very mild in my opinion. If you're watching the first FMA and not Brotherhood, than I would say AoT is much more violent. Brotherhood isn't quite as bloody/gory as AoT, but its closer to what you'd see in AoT than FMA (2003) or Death Note.
I'm almost 100% sure that two very significant characters in AoT are gay; however, I don't think any romantic relationships result in the show--gay or straight.
Again, I've only seen some AoT here and there, but I'm fairly confident the information I'm giving you is legit.
I'll end this off by saying Death Note is not a 17+ show. It is very mild compared to other "17+" shows I've seen. It probably gets that rating for the concept of the main character being a psychotic killer, rather than the actual content of the show, if you know what I mean.