I would suggest Glen Cook's Black company series[1] It is written from the perspective of mercenary grunts, so they are no "heroes" in the usual sense since they are not always hired by the good guys (and it is hard to real divide the world between good and bad, it is more a greyish blur). It also has the kind of gritty feeling of ASOFAI, at least in the first books. I won't spoil anything by saying that most characters are pretty expendables, the body count is rather high.

It is fantasy but without the usual dwarves, elves or dragons, but there are much more magic than in Georges R.R. Martin and it is sometimes used as deus ex machina, and is a bit over top for my taste. (However in an interesting twist the black company has only a handful of not very powerful wizards, and since they can't overpower the enemy though sheer power, their magic use is basically used as form of advanced misdirection or psyops)

I would say that the writing is a bit simpler and the characters are a bit less fleshed out than in ASOFAI, but the pace is pretty riveting as well. From my recollection, it reads more like a mystery novel, most events do not make immediately sense, and you are trying to find out who is really pulling the strings behind the scene. On the plus side, even if it is long, I think the story is more focused and go less astray than ASOFAI. (I enjoyed GRR Martin books, but sometimes it feels like he can't help adding new characters or subplots for no particular good reason)

IIRC it is/was pretty popular amongst soldiers stationed overseas.

[1] https://en.wikipedia.org/wiki/Glen_Cook#The_Black_Company

PS : If I was a television exec, I would try to secure the rights for a TV adaptation ASAP. I am not sure it would work as well as GoT, but it could be a very palatable successor.