i used to have a medela mini electric and found the suction too strong on the lowest setting and felt like my nipples were being ripped through the cap (and the cap i had was only the hard one but i think you can get a soft one?)
Just on this, if you go with Medela it's SO important to make sure you get the correct size breast shields - it makes all the difference! Expressing shouldn't hurt but I learnt the hard way by using breast shields that were too small initially. The larger ones made all the difference.