Performance is pretty easy...crowdsourced benchmarks give a good view, as they're easy to run and so far they all look very consistent. It's obvious that there are no major gains from either manufacturer in that department. While it seems that most of the benchmarks show the Samsung having a very slim lead in performance so far, it's so small as to be completely irrelevant. No one can feel the difference in a 0.5% speed gain.
Battery life is more interesting given the very few data points we have, but this will be very difficult to test well. Someone will need to get a BUNCH of phones (at a bare minimum, 10 of each kind...would be better if the number more approached 50 of each), and did clean installs with the only thing on them being geekbench (or another battery test suite), and run each phone a few times. THEN we might be able to say there's a trend with battery performance based on a chip. Unfortunately, I don't think any publication is going to care enough to test a huge volume of phones.