I prefer writing third person simply to make handling different characters easier and make it more cinematic. My favorite parts of movies are often switching to another character's perspective in a scene and seeing things from a different angle, which would be incredibly hard to justify in a first person novel.
When it comes to reading, I don't really have a preference. It's hard to have a preference when I don't want to be reading crap.
Third person for me is just easier to convey everything when I have a large cast of characters to work with and want to incorporate their own independent development arcs; the best part is we can divulge all the details or limit the extent of the 3rd person POV in order to build a sense of mystery or suspense. You can't really achieve the same effect through first person without the requirement often being the MC to be the sole catalyst for said development, and even then you have to really be selective about it. It's feasible to make a series out of 1st person POV stories but I usually see them in the form of coming-of-age diary type stories like Dear Dumb Diary, the Wimpy Kid franchise, etc. First person stories seem to really only exist within 1 long story arc, rather than a continuous string of different arcs that eventually coalesce in the end for a final definitive ending. The world the author builds for a first person POV also seems far smaller compared to a 3rd person-- it may likely be due to the fact many I've read were grounded in our reality, but elements of fantasy are not as extensively explored so much as you really only see how such elements directly impact the MC's little bubble in a specific frame of time. 3rd person gives me greater liberty to develop a world that exists independently of the MC if I want.
I have rarely, if ever, written in the 1st person but I'm not against reading in 1st person. Based on the number of books I've read where a 1st person POV was used to tell the story, it seems most useful for stories where we are mainly fixated on the development of just the main character who is undergoing a lot of change under a short time. Usually the world around them influences them, with a limited visibility radius of that world, and not the other way around (though to an extent they do influence the world around them but on a smaller degree). It's probably the most effective way to really help the reader sympathize with the MC and bond with them by giving them full disclosure to their thoughts and feelings; which might be why so many books written for school-age children & teens are often 1st-person since they tend to have an easier time relating to them in that format.
Those done in a journal entry/diary style or a series of letters being written to an important person in the MC's life they indirectly speak to are especially very effective since we experience the story in a seemingly present-tense lens at the same pace as the characters mentioned. It's good for building suspense and really lends itself well to telling stories with more serious, carefully researched topics like familial abuse (Rules of Survival by Nancy Werlin), the trauma of sexual abuse at a young age (Speak by Laurie Halse Anderson), eating disorders (Wintergirls by Anderson & Skinny by Ibi Kaslik), and other social issues. First person telling of the MC experiencing these issues really drives the inherent visceral feeling of these problems home to your reader and, if handled well, can be a way for people who have experienced them first-hand to cope while also being a tool for spreading awareness and sympathy/support. Third person limited can pull it off too, but a large majority of the works I've seen dealing with these topics default to 1st person for good reason.
Never had a preference for reading either POV because I've never really recalled a time I've picked up reading a book and saying to myself, "oh golly gee, this book would be way cooler in the 1st POV". I don't think it really impacts the quality of a story on the bottom-line very strongly since it's really just a matter of what the author finds best to use for revealing their world & character. It's as unconscious a decision as choosing your character's hair color imo. The only time I've ever wanted a 1st person POV story to be third person was really because the MC was painfully annoying and incessantly rambled. The book itself was just mediocre in many aspects that the POV wouldn't have made a difference on.
It really depends on the story for me. Sometimes, it flows better for me if I write in first person. Other times, it flows better as third person. And for reading, it doesn't really matter to me whether it's first or third.
Depends on the context. I only write first person if it's something regarding me, but other than that i prefer to be in the seat of an "observer" if you will, and third person feels more comfortable for that.