Both not bad options and both good for career development. Some things to consider:
1)You mentioned being out of school 11 years now. Do you have the capacity to go back? (meaning, can you afford to either do night-time work or full-time MBA work with your current life responsibilities, financial situation and work responsibilities?)
2)You said you like the accounting work and have always been interested in the investments route. Do you like each field equally or one more than the other?
3)You said the CFA seems a lot simpler--sorta/kinda. Yes, you are correct in that just to sit for the CPA you need the 150 hours which means either going the master's degree route (which to me makes a lot more sense because if you need to sit in a classroom, why not get a degree?), or just rack up the 30 or so hours in useless coursework. But, once you do that, you can sit for the exam on just 1 day and be done (not factoring in studying if course).
4)Where do you see your career going? Do you want to stay in accounting, but just see the possibility of not having a CPA hurting your progression? Or, do you genuinely want to switch career tracks and go down the finance route? Obtaining the CFA will greatly help in a potential career switch. Even in interviews being able to say, "I'm going to take Level 1 in the next x months" or "I've passed Level 1" will help. The answer to preceding career questions will greatly determine how you should think about your choice.
5)The CFA, as you know, is not a one-off thing. The CFA route is a medium-term commitment. Yes, anyone can sit for the exam but the 3 different tests over 3 years requires a certain level of sacrifice. Can you afford the study time in this stage of life? Do you foresee anything getting in the way over the course of 3 years that will break up the string of time?
Bottom line: either certification is good to have. With your finance undergrad background and accounting work experience you can easily go either way....or both.
Good luck.