The best toilet bowl cleaner brand is Clorox Toilet Bowl Cleaner.
Another great toilet bowl cleaner is Zep Toilet Bowl cleaner and also Dollar Generals Brand of Toilet bowl cleaner.
I find that the cheaper Dollar General Brand of Toilet bowl cleaner also works just as great as Clorox Toilet Bowl cleaner and sometimes better.
I've easily removed toilet bowl rings and other grime from my toilet bowl with Dollar General Toilet Bowl Cleaner.
In tank toilet bowl cleaners also work great to help keep your toilet bowl clean but you should still use a toilet brush and toilet bowl cleaner that you put directly into the toilet bowl.
You can also use some bleach to occasionally clean and disinfect your toilet but using too much bleach can cause damage to the toilet bowl.
CLR can also be used in toilet bowls and in your toilet tanks as well.