According to a 2011 study, menstrual cups are the shit. Not only are they cheaper than tampons (a $25 cup lasts you 10 years), but they keep your pc muscle tighter and your vagina more lubricated.
It makes sense since any sort of tampon or pad is going to have bleach and/or other chemicals that can dry you out - and I'm not even going to speculate of carcinogenic additives. Pushing out to insert and release your cup from your vagina as well as pulling in to get it in place is a monthly workout for your pc muscle (a happy pc muscle is an orgasmic pc muscle).
I love my cup and have my post-birth model ready in my make-up bag. I haven't started menstruating because I'm still breastfeeding but, now that Grayson is sleeping in his crib (no night nursing), I expect it any day. Last xmas I gifted several to my women friends and family but I doubt that they're using them. The idea of emptying a cup full of your menstrual blood groses out some people like no one has ever fished out a bloody tampon or bled through a pad.
Realizing just how much blood I released every month was fascinating because it really wasn't that much. And I feel more connected to my body going through the process of penetrating my own vagina and discarding my menstrual blood. So wish someone gave me a cup when I was a teen girl. It would have changed my life.