I would prefer the paramedic training, however, I am biased having 10 years
paramedic experience. My former EMS medical director for 9 years is a DO which is 1 of many reasons I preferred a DO school over allopath (nothing wrong with MD though).
The benefit of your paramedic over RN is this: At times (in between all the drunks, drug addicts, and pregnant for the 3rd time 16 year olds), you will develop a thought process where you have to think critically and act real fast to save a life. You dont have time to get the opinion of the doctor, you just have to do it. My medical director says we are trained like physicians; albeit, we dont have anywhere near the knowledge base of one. This type of decisive thinking will serve you well as a doctor.
As a nurse: you are not trained to act like this. A good ER nurse knows what they are looking at many times, but they cant do anything about it because the doctor has to give the order. That type of dependency on someone else, in some people is hard to break, so, they dont develop the type of decisive action taking that you develop as a paramedic. As a doctor, that is training that you don't want to follow you. However, RNs learn more book knowledge and have a better handle on many disease processes that as a paramedic you receive no training about, but are expected to know. Plus they make better $$$$$$$. I am not degrading the nursing profession by any means, you will see how important to your practice that they are.
Personally, I think the instinct you learn as a paramedic will carry you farther than knowing a disease process. You have to learn those in med school anyhow. I say go for the paramedic as long as it is an intermediate step in your career and not a career choice itself. I dont know how some of the old timers in EMS do it, it is a hard lifestyle. Good luck in you choice.