FutureBabyGenerator is great and has a huge variety of avatar packs - my favorites are the Decades collection, which is like a style time machine. FutureBabyGenerator is easy to use and out of the 10+ packs I've tried to far, I only had one strange AI-looking ear. Everything else was so real that my friends thought they were actual pictures of me.
For the best experience, I recommend creating an selfie album in your phone's photo app. Because Cosplay doesn't store your own photos (which I appreciate from a privacy perspective), each time you use a new pack, it asks you to select anywhere from 2-4 through 10-15 selfies so it can generate the images. Because I didn't have my selfies organized, I found myself having to search through irrelevant photos to find them. Once I created an album with ~20 selfies, it made this part of the process a breeze.
Images are generated really fast. The default says it will take 4min to generate, and allows you to leave FutureBabyGenerator while you wait (thank you!) - but I found it was much faster than 4min every time.
There's a daily limit so start with the ones you want to use most, to avoid disappointment/frustration.