if i were doing a core java stuff, i would have gone with developer position though not easy and no matter i do lack logical mind..
i understand logic are creation of mind and any mind is capable of creating it.
java - many things to learn and more you learn, more you are eligible for quality jobs which are in large quantity in the market.
big data - hot in the market. really hot. being a big data pro would be much beneficial.
selenium - probably not so many things to cover like in java but still it may be good option for being a tester. (not much idea about selenium)

decision is yours.