Who are the Best and Worst Current Singers?

It seems that most people on the internet nowadays don't really have high regards for the current generation of singers, particularly pop stars, compared to the iconic legends (Freddie Mercury, Aretha Franklin, etc.) of the past but I think there's plenty of incredibly talented vocalists popular right now.
So like the title says, who do you think are among the best singers and worst singers of the current roster, mainstream or lesser known? And who do you think is overrated/underrated?

Off the top I'd say
Best - Lady Gaga, Florence Welch, Beyonce, & Jessie J.
Worst - Adam Levine, Taylor Swift, Jennifer Lopez, & Selena Gomez.

Best male and female: Jared Leto and Jessie J/Adele

Overrated - Ariana Grande, Lorde, Taylor Swift.
Underrated - Jessie J, Lana Del Rey, Shakira (in non spanish speaking countries)

i think shes more hip hop and pop but yeah she sucks.