To find the most popular fashion influencers in your niche, you need to do some research and analysis. Begin by defining your goals and criteria - what are you trying to achieve with your influencer marketing campaign? Who is your ideal customer and what are their demographics, psychographics, and interests? What kind of content, style, and tone do you want to associate with your brand? How do you measure the popularity and relevance of an influencer? After that, use tools like Google Trends, Keyword Planner, or Hashtagify to search for keywords and hashtags related to your niche. You can also use tools like BuzzSumo, Upfluence, or AspireIQ to find and filter influencers by keywords, categories, followers, engagement, location, or other metrics. Once you have a list of potential influencers, evaluate and rank them based on your goals and criteria. Utilize tools like Social Blade, Klear, or HypeAuditor to get more data and insights on the influencers' performance. Additionally, check their profiles, posts, comments, and reviews to get a sense of their personality, values, and reputation. Finally, rank the influencers by their popularity, relevance, reach, engagement, authority or other factors that matter to you.