It will take a while before Ubuntu touch or Firefox OS get up to speed, however the advantage of having them is that they are open source, really open source. In contrast, a lot of the good parts of Android are actually proprietary Google apps- maps, music, calendar, search, Play store, etc. Yes, there is an open counterpart, but all the good features are in the proprietary version. Try using an Android phone without a Google account.
This goes hand in hand with the other advantage for an alternative OS that is open - Privacy. To use all the good features in Android, you have to subcribe to the Google Experience and also give up your privacy. This isn't a bad thing if we get something worth the price we pay, but it is nice for people to have a choice. The competition will only benefit the consumers.
It will be a rough road to switch to an alternative OS. Google is creating their own walled garden, and as the walls get higher, it becomes harder and harder to switch. Ask any iphone user if they would try android for 1 year. The apps, purchases, and integration make it hard to move to another OS. Again, I don't fault the companies for using that strategy; it's actually quite clever. As long as there are other OS's that are open, then I don't have to be their cash cow that gets milked daily in exchange for being allowed to roam around the garden.