Before we get any further let me just let you know of course your favorite series isn’t garbage. In my opinion no series is garbage not even the infamous School Days (even though I know that might sound a bit crazy though to be fair haha). With that all said you may then ask if there are no series that are garbage then why aren’t they all popular and well received? Well this is due to two main reasons the first being popularity does not equal quality. On that note if you’re wondering what makes a series popular you can read my thoughts on that here and learn my opinion on that topic. As for the second reason it’s that I truly believe it’s what you like that truly decides what makes a series good. If you’re someone that enjoys only mecha anime then you will probably really like Gundam but you may think idol anime are garbage despite them being rather popular (especially Idolmaster and Love Live) conversely if you like idol anime you might find mecha anime to be boring.
To conclude like many things it’s all about your opinion and perception. I hope this makes my stance clear on the topic. In addition with this in mind I will be starting a mini series on controversial anime soon so stay tuned! As always thanks, -Cas