What is best for your career given that the future is -- by definition -- not knowable and that the past and present are not necessarily indicative of the future?
After all, what is better today may not be better tomorrow and what is better tomorrow may not be better the day after. We live in a world where all technologies are in a state of decay, and our environment is rife with disruption and innovation.
Go deep (specialize) just enough to be unquestionably proficient, but not enough to be one of the world's foremost experts. Go broad (generalize) just enough to be learned (well-informed) in discordant technologies, but not enough to be omniscient (all-knowing). I call this type of a person a "genspec", a generalist-specialist.
For example:
1. It's more useful to learn functional programming, object-oriented programming, procedural programming, etc., than to learn e.g., 3 different object-oriented programming languages.
2. It's more useful to learn embedded development, mobile development, web development, etc., than to learn e.g., three different mobile development platforms.
3. It's more useful to learn e.g., 3 different OSs than to learn e.g., 3 different distributions of a single OS.
Optimize yourself for change, adaptability, and continual learning of many materially dissimilar topics.
That's what's best for your career.
Whether you are looking for employment with someone else or starting your own company, having a broad set of skills is always valuable.
There is nothing worse than doing something you don't like, no matter how good you are paid for.
Do what you enjoy and will be a great for your career!
I want android or something more open to win. They don't have the brand though.