Server side analytics advantages: - No overhead on your website, because no external resources are loaded - Not affected by content blockers - Can track resources other than web pages, like images or redirects - Show resources that could not be found
Client side analytics advantages: - Can capture more data about the user, like device size, browser and OS - Better track user behavior, like time spent on each page - Provide real-time feedback about visitors - Usually easier to setup (3/8)
I've been playing around with different analytics options on my blog recently - Netlify on the server and Plausible Analytics on the client side. The results from 7 days comparison turned to be quite different [0].
The server side tool shows much more views across all pages in my blog. I think this is because the pages are accessed many times from automated systems that don't run JavaScript and are therefore not counted on the client side. This happens when you post a link on Twitter or WhatsApp for example, because their websites or clients then make a request to fetch the metadata of the page and display a card preview. Therefore, it counts on the server, but not on the client side. A perfect example is the draft article, which I only sent per WhatsApp to my wife for proof reading. The difference there is just 2 views (I guess one preview each on my and on her phone). I sent all other links to several people and posted them on Twitter and Reddit.
You can also somewhat see this effect in the referrers [1]. The server side tool counted many hits from a RSS reader and Google Translate (my parents in law reading my blog in Bulgarian :D). The preview requests from Twitter and WhatsApp are probably counted as direct traffic.
I think client side analytics more realistically count the number of people reading my blog (even if not many). However, there are cases that can be captured only on the server side (for example Google Translate). So, the best way would be to use both or maybe even make a service that combines client and server side - I think there is a lot of potential there!
[0] https://pbs.twimg.com/media/EY-IqtdXsAAJvu9?format=jpg&name=...
[1] https://pbs.twimg.com/media/EY-J0c8WoAEwn2J?format=jpg&name=...