Try also Ibarrak or
http://www.refugioplazademulas.com.ar/index.htm (speak to Eduardo or his wife Mo). They might be a little more expensive than the rest, but they are the best tailoring expeditions, are the first to get into Aco., the last lo leave every season, and probably the most experienced service provider in the mountain. They are a little “posh” and not very well known in the USA (they cater mostly Europeans), though they have been in the mountain for more than 20 years (I understand they have the highest summit record). Last Nov. I went solo to Aco. (only used their mules) and the first three guided expeds. (and the first to summit) were theirs.
INKA is ok, not as massive as Aymara, but not as personal as Ibarrak. Grajales, they say is not anymore what it used to be. There are many other, but I don’t know them.