The answer depends on a lot of factors and bits of information not provided. For instance: What's your competition? How does your house compare to the competition as far as number of bedrooms or condition of bathrooms? If you said that your competition all had 5 bedrooms and you only had 3, then my first thought would be that you might want to add a bedroom. On the other hand, if you said that all the competitive houses were the same model in the same community--so they all have the same number of bedrooms--but that some had upgraded master baths, then the bath might be the thing to consider.
Just one quick thought, too: $50,000 to remodel a master bath is a lot in most communities. Again, I don't know your house or area at all, but $25,000 is a lot more in the range I'd expect...perhaps less. And recognize that while remodeling the master bath will certainly make your house more saleable, it won't return anywhere near 100% of your investment.
And if you're not planning on selling right away, you have to factor in your own preferences. Which do you need and want more? Which is of more value to you? Even though, as I said, a major remodel of the master bath won't return your investment, still--if that's what you want and what you'll enjoy--then that's what you should do.
Hope that helps.