Reasons why I chose the Ypsopump were:
1) size (small) ... especially against Minimed (which I had used the 20 years before) where each pump got bigger and bigger with lots of stuff added that I never used(or needed)
2) easy to use (touchscreen; very few functions; not overloaded)
3) pre-filled cartridges available (at least for the insulins I am using)
4) very responsive customer service and support from their team (i.e. induction into the pump)
I was not so happy with the infusion sets at first ...had more injection site reactions than I had on the Minimed. thus need to ensure I change the set every 3 days (while with Minimed I was able to go longer without issues).
Now, since they collaborated with CamApsFX and developed the my-life.loop system I am even more convinced. Very happy user (Ypsopump, FS3, mylifeloop).