You can still write websites using the technologies you're familiar with, such as Rails. If your goal is to get something out the door, then I'd suggest you pick something that feels familiar and comfortable, or will hold your attention, and is good enough for the job.
No matter what you choose, there's going to be pro's and con's. That's not to say that each choice is equally good -- some options are on balance worse than others, and the optimal choice also depends on the nature of your project. But chasing the optimal choice can cause delays. I've personally been guilty of swapping a key part of my stack (the website part) half-way through a project, just because I wanted to do it a different way (for that project though, it did not matter).
With that out of the way, my bias: I strongly suggest you pick postgres for your database, which is a favourite on HN for good reason.