This is completely subjective question but I will try my best to lead you in the right direction.
First of all, every preset has its own concept. So, decision highly depends what do you expect from the preset. For example, if you are looking for constant color tones for your Instagram feed, I would first recommend you to decide the color tones because you'll set your Instagram's future, no one would want to continue with unwanted tones. Many Bloggers and Influencers prefers Pink or Brown presets because they look pastel and rich. These tones becomes their Brand color and they use the same preset for all of their photos.
Pastel tones are great for Branding. Also, they do not tire eyes as they are not that vivid. But here is the second type of presets arises the "Vibrant" ones. These ones to attract audience attention by increasing the brightness, clarity and vividness of your photos. They are mainly for Holiday photos with blue or green backgrounds. You cannot use them for each and every photo.
Third ones are for the unique niches such as Newborn, Wedding, City, Car or Food etc. Those are set for the niche and using them for other purposes may not result well.
Whether you are a Blogger or Influencer or Hobbyist or something else, always look for presets that fits well in your scenario. If you are going to post a Food photos choose from Food Presets.
There are many sources to find Lightroom Presets. You can directly Google the preset type you want or go to digital marketplaces such as Etsy or Creative Market to make custom searches. I hope this post and this website will lead many people choose correct presets for their needs. Presets in this website will always be Free.
Alright, you can always check out all of the presets available in this website as a simple list on the Preset Index page.
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