I've also run into MM people in Peru and Ecuador. It's a good company but you can also try a local company. In January I did a mountaineering course with Andean Face, which is an operator of companies on the likes of MM, uses the same guides, same itineraries, but cheaper.
Ecuador guides are strong and great with novices, and if January/February is the only period you can go Ecuador is a good choice. Approaches are easy (although you usually drive to huts) and you can concentrate on learning. Downside is the weather, which is unpredictable.