  The exponentially growing number of scientific papers stimulates a discussion
on the interplay between quantity and quality in science. In particular, one
may wonder which publication strategy may offer more chances of success:
publishing lots of papers, producing a few hit papers, or something in between.
Here we tackle this question by studying the scientific portfolios of Nobel
Prize laureates. A comparative analysis of different citation-based indicators
of individual impact suggests that the best path to success may rely on
consistently producing high-quality work. Such a pattern is especially rewarded
by a new metric, the $E$-index, which identifies excellence better than
state-of-the-art measures.
