Breast pump manual vs electric

I'm picking up my breast pump next week. The doc put an order in for me which I read was cover under insurance but I wasn't asked if I wanted a manual or electric pump. The lady from the company called me and said she'll set one aside for me. (I hope it's not a crappy or cheap one). Can someone give me insights on which meaning manual or electric had worked best for them? And does it make a difference in how much milk can pumped within a certain period (ex: manually pumping 4 oz in 25 minutes vs electronically pumping 4 oz in 15 mimutes)- those were just some random numbers. This is my first time breastfeeding. Help and thanks!