I think we've never had annual statistics to praise the people writing and editing code? Let's try. (Though many areas and people are missing and data might have bugs.)
20 most active on-wiki gadget and MediaWiki:Common.js editors [1] in 2018: 846 Od1n 491 DAlangi (WMF) 333 Jack who built the house 192 ToprakM 187 Épine 179 Wim b 155 Krinkle 150 HastaLaVi2 124 محمد شعیب 124 Peter Bowman 122 Yamaha5 119 ESanders (WMF) 95 TheDJ 88 Vinhtantran 86 Nirmos 82 Alex brollo 78 Bodhisattwa 69 SM7 68 আফতাবুজ্জামান 68 Suzukaze-c Longer list in https://phabricator.wikimedia.org/P7954
20 most active Gerrit submitters [2] in 2018: 3005 Legoktm 1885 Marostegui 1875 Umherirrender 1395 Hashar 1379 Esanders 1192 Jforrester 996 Krinkle 916 Andrew Bogott 882 Dzahn 855 Jcrespo 786 Thiemo Kreuz 783 Elukey 740 Urbanecm 718 Ejegg 717 Reedy 691 Robert Vogel 679 Addshore 655 Jdlrobson 653 MarcoAurelio 632 Matmarex Longer list on https://wikimedia.biterg.io/ under "Gerrit" [2]. For more info, see https://www.mediawiki.org/wiki/Community_metrics (and its talk page for anything related to wikimedia.biterg.io itself).
There are more potential statistics (Github repositories [3], Gerrit reviewers [4], Module editors, etc.) that could be interesting - if someone has ideas how to get such data [5].
Cheers, andre
[1] by pulling the sitematrix and getting the authors of the revisions of all MediaWiki:Gadget-* and MediaWiki:Common.js pages per site via https://gitlab.com/aklapper/wikimedia-wikis-gadget-editor-stats/ (which welcomes an actual developer to write this in a proper language) [2] https://wikimedia.biterg.io/ under "Gerrit > Overview" in the "Submitters" panel, after setting "author_bot:false" in the search field and setting the time frame in the upper right corner. [3] https://phabricator.wikimedia.org/T186736 [4] https://github.com/chaoss/grimoirelab/issues/58 [5] Did not spot anything on https://www.mediawiki.org/wiki/Development_statistics