Hi boaconstrictor,
I am currently graduating from HEC Lausanne and will be starting next year in Zurich at the ETH-UZH MSc QF. I am an atypical student for the programme since apparently a majority of students come from more quantitative backgrounds (mathematics, physics, engineering, etc.). What is your background?
Curricula
Comparing the MSc Finance from HEC Lausanne and the MSc QF from ETH-UZH is like comparing apples and oranges, as noted above. HEC Lausanne's MSc Finance is NOT a quant degree, although you can choose a certain degree of exposure to quantitative methods for finance. It remains a more general degree with a more practical orientation. Don't let the FT ranking sway you, the MSc QF isn't on it because it's not a MSc Finance, simple as that. So comparing curricula is futile, it all depends on what you want to study, and what your objectives are. Unfortunately, I couldn't find worldwide rankings for QF Master's degrees, but they would quite likely score quite high.
Institutions
Once again, comparing HEC Lausanne to the ETH-UZH pair is difficult, since they are known for different things. HEC Lausanne has a limited international exposure. I'm speaking from experience as I'm currently studying in Hong Kong, where people mostly only know about St Gallen in Swiss business schools (sometimes also the IMD in Lausanne for its MBA). However, HEC Lausanne is quite strong, and the FT ranking, along with pronounced promotional efforts from the faculty's administration, will certainly help boost this exposure. ETH definitely has a very strong reputation. Quoting from memory, some rankings place it as the number one institution worldwide outside anglophone countries. It also benefits from the reputation of being Albert Einstein's alma mater. I'm not sure about the UZH, but it is quite known within Switzerland - especially its Economics department.
The city also has a role to play, and Zurich is very well known internationally as a strong financial center.
Finally, things like quality of life and general attractiveness of the two cities are entirely subjective. The previously noted opportunity to learn German is a huge plus, especially if you're considering to work in Switzerland. I myself will be "cashing in", so to speak, on this opportunity. While being Swiss, I was born and raised in Romandy - the francophone part of Switzerland, west of the Röstigraben. Since you accepted the offer to the MSc QF, we will most likely meet in Zurich in a couple of months. Uf Widerluege!