How to find the leading researchers in a new field I'm in computer sciences, in applied Machine Learning. I often have to switch applications and I find it cumbersome trying to discern the really good and bad works by doing a large survey.

Whenever you are new in a field, how would you direct your survey to find the people doing seminal work in the area, for example in the specific case of Latent Dirichlet Allocation in Computer Science, you can always go to a 2003 paper by Blei, Jordan and Ng. While if you are a seasoned researcher of the area, you already know this paper is relevant, how a newcomer would find such paper?

Do you ask experts in the area? Do you go by number of citations (I often find this deceptive, particularly in Bioinformatics)

I'm interested in this because I'm switching applications now, and I would like to know which group's work I should be following or which person's papers I should be reading.
Problem is that you hamstrung yourself by eliminating the only correct strategy: doing a long literature survey yourself. You wish to rely on proxies, and sometimes surveys can do that for you, but other people's opinions of "good" and "bad" are just that: opinions.

The only way to really get a sense of good and bad is to read a LOT, think a lot about what you read, discuss with people who might know more about the area, think a lot more, read more, and repeat.