If we are talking about paper reviews, what I am looking for in a paper as a reviewer is neither simplicity nor complexity. I am not even looking for "novelty".

If we are talking about paper reviews, what I am looking for in a paper as a reviewer is neither simplicity nor complexity. I am not even looking for "novelty". What I am looking for is a thorough and thought-provoking empirical analysis of a problem. I see plenty of submissions where 1) authors propose a system that is clearly a monstrosity Frankenstein patched together from a dozen of existing ideas - clearly a successful attempt at getting "bold numbers" using as many new shiny toys they could get their hands on without analyzing failure modes of either part in depth; 2) a simple modification of an existing method that accedentally improves the performance of the system but still lacks proper empirical or therotical justification of why this modification helps. While the second type of papers has at least some marginal value to the community or the reader, I still find such papers mostly useless. What brings value to the reader is a phd student who stared at the problem long enough to find quantitative and verifiable confirmations to his intuitions about the problem that lead to reproducible observations with predictive power. Ie "we experimentally verififed that indeed X affects Y exactly though the mechanism Z described in this paper in all cases, this helped us to improve metric A by B%, agreeing with Z". Not "we did X, and we saw A increase by B%", regardless of the complexity of A. Not all reviewers agree with me, sadly.