The best use of MRPs is purchasing TC Direct products. Because with that you get to earn SVP which will help you advance to the next level. I think among all those products, the single TCredits gives the maximum returns. You can purchase it with 126MRPs and you will get 102 VPs in return. Isn't that great?!
When I'm not in need of points, I sometimes purchase products from other ECAs with MRP. These are usually things I personally need.
Hope I've been helpful?