We based ourselves at Hub Porteno during our two week trip to Argentina and Uruguay and it was a great choice. The staff at the hotel were brilliant - they couldn't have been more friendly and helpful. They gave us tips on what to see in BA - eg. what tango show to go to (there are a lot) - arranged for us to leave things at the hotel whilst we travelled elsewhere in Argentina and Uruguay. Great service. The hotel is really well situated in Recoleta, down a quiet street next to the Vatican Embassy. Always felt very safe and we had no problems at all. The restaurant in the hotel is excellent, although not cheap - the wines were the best we had during our entire trip. Breakfast is great (eggs benedict particularly good). Our room was by far the best we had of any of the hotels we stayed in in Argentina and Uruguay - huge very comfortable bed, fantastic bathroom and shower (including a two-person jacuzzi bath), loads of storage space, fridge etc. Great roof terrace for relaxing in the afternoon / evening. We liked the cakes and sandwiches provided at 5:30pm in the guest public rooms as an afternoon snack.
I couldn't fault the hotel or the staff. If we come back to BA we will definitely stay here again - strongly recommended.