I went to Hospital Aleman a couple times when I first arrived here. I wasn't impressed at all: I waited to see the doctor for a good amount of time (granted, I didn't have an appointment) I didn't find the examining room particularly comfortable or nice, and the doctor saw me for two seconds told me I had gas and rushed me out. It wasn't gas or anything near it, and where I was finally taken care of was Hospital San Camilo in Caballito, which is a Catholic hospital. I never hear anyone speak of this hospital but it was honestly the best I have been to. Appointments within 7 days in most cases, the guardia or emergency room is always well-staffed and quick-moving, night and day, and the doctors really seemed to pay attention to my concerns. The administration staff are helpful and (get ready for it) efficient, and I am actually sad that I no longer live near that hospital. I have OSDE medical insurance which covered everything, but I think they accept others.
At Hopsital Aleman I was also put off by the long lines to do anything-- just to talk to the admin, the guardia lines, and especially the lines to drop off or pick up tests. And this was a weekday morning! Maybe it was a crazy time for them, but I honestly wouldn't get an 'only Hospital Aleman' insurance plan.
I have friends who go to the Swiss Medical in Palermo I think it is, or at least the closest to Palermo, they say it is like a 5 store hotel, no waiting, always wonderful.
Best of luck.