I am not not sure what a medical engineers are doing exactly, but it seems that the pay grade could be a little higher even if the working area seems a bit smaller. Software engineer is great and it's not like the future needs less software. From the software area you have a wide range of areas choose between.
You should also consider where you live planning to live city countries becouse the are you living in might be stronger in some areas.

What is a medical engineers do?

To me the software engineering the way to go. But if you can't choose. Find the favorit spot in the city, sit there 5-10 minutes and think about what choice you would like when you geting old and can't work anymore. The right one will come to you...