I don't rate books in my typical review posts, but my ratings of every book I read are documented within my Show Us Your Books lists (since January 2018). If you follow me on Goodreads, this is the same system I use to rate there as well.
5 Stars ⭐⭐⭐⭐⭐
LOVE LOVE LOVE. I will recommend a 5-star book to anyone and everyone and probably won’t shut up about it. I absolutely need to own a 5-star read, so I can lend it out and have it available for re-reads. I usually have half a dozen or less books in this category each year because they need to be really outstanding to warrant 5-stars.
4 Stars ⭐⭐⭐⭐
REALLY liked it. I will recommend a 4-star book to someone I think would like it - depending on interests/genre - and like to have them as part of my collection (for the same reasons as above). I’ll probably rave about this one a fair amount as well.
3 Stars ⭐⭐⭐
Liked it. A 3-star book was good. I didn’t feel like it wasted my time and walked away with an overall positive feeling about it. I give the majority of the books I read each year 3 stars, and I don’t consider this rating to be a bad one.
2 Stars ⭐⭐
Not a fan. This book just didn’t do it for me. It may have been a bit of a waste of time, or it may have been an experimental genre/topic that didn’t work out. I’m not upset about the time I spent reading it; I was likely just hoping for more. I didn’t hate it, but I didn’t really like it either.
1 Star ⭐
Hated it. Pretty self-explanatory, and I don’t hand a 1-star rating out lightly. Like the 5-star books, these are pretty rare.