Although I prefer YC, but just in case I get rejected for whatever reason, is it okay and ethical to apply with other accelerators along with YC to increase my chances? Did anyone ever do that?
Of course you can apply to any of these you want. But the best approach is actually taking the application process as a learning experience in itself, since it's unlikely to result in the direct benefit you're seeking.
In other words, if you're going to apply, make the most of it regardless of the outcome.
In other words, if you're going to apply, make the most of it regardless of the outcome.