Oh dearie! A manga thread!
I have a lot of series that I would consider my favourite, but there are two different categories of favourite for me. One contains the works that are so technically refined that they set the standard of quality for all the rest. The other is more emotional, and consist series that aren't necessarily as superb as the former list, but have had an intimately constructive influence on the person that I am, and the style of own creative work.
For an example of the former, I would say Koe no Katachi--but someone else will most definitely name it as well, so Shoujo Shuumatsu Ryoukou. It is just so devastatingly poignant how much humanity it is able to convey in such an otherwise bleak and stripped down setting, tiptoeing that precarious line between fuzzy slice-of-life warmth, and sobering apocalyptic realizations. Simply brilliant.
An example of something personally dear to me--that I would be completely unashamed of confessing to--is xxxHOLiC. It is the work that ingrained in me a taste for philosophical interpretations of the occult, an attention to detail in every aspect of the presentation, and pointy-chinned noodle-people xD... It was also a very relatable coming of age story for me, as everything the protagonist encountered and every lesson he learned touched me very deeply, as though I had been the one experiencing them myself. Watanuki Kimihiro remains one of my favourite characters until this day.
To keep this brief I would like to answer that CLAMP is one of my favourite authors, even if their overly diverse catalogue of incomplete and experimental projects can be a little hard to tune in with at times. As for whether I even like manga, I love to hate and hate to love it; it's already an inseparable part of my existence, for better or for worse.