Hi Kitzat welcome to Scarleteen!
IUDs and the implant are up top when it comes to effectiveness in hormonal methods. The most effective option however would be to combine any of these methods with condoms, which will have the benefit of adding STI protection, and whittling down the likelihood of unwanted pregnancy to a smidge.
Have you looked through our
Birth Control Bingo! resource?
When it comes to side-effects of the various methods, it really is very individual. However you can have an IUD or implant removed if they aren't working for you, and oral contraceptives, or the Ring are other methods you can stop yourself if you need to.
"In between two tall mountains there's a place they call lonesome.
Don't see why they call it lonesome.
I'm never lonesome when I go there." Connie Converse - Talkin' Like You