I would like to nominate @RaisinTen. They have been very active and valuable lately. I think everyone who pays any attention at all to the repository has seen their activity but to do the customary summarization anyway (copy/pasted from Mateo's recent nomination):

@RaisinTen:

Commits in nodejs/node: https://github.com/nodejs/node/commits?author=RaisinTen
Pull requests and issues in nodejs/node: https://github.com/nodejs/node/issues?q=author:RaisinTen
Comments on pull requests and issues in nodejs/node: https://github.com/nodejs/node/issues?q=commenter:RaisinTen
Reviews on pull requests in nodejs/node: https://github.com/nodejs/node/pulls?q=reviewed-by:RaisinTen
Help provided to end-users and novice contributors: https://github.com/nodejs/help/issues?q=commenter:RaisinTen
Pull requests and issues opened throughout the Node.js organization: https://github.com/search?q=author:RaisinTen+org:nodejs
Comments on pull requests and issues throughout the Node.js organization: https://github.com/search?q=commenter:RaisinTen+org:nodejs