This post was created by Roberto Blake on X / Twitter, but it's very good advice! If you're not sure which fonts to use, this is a list of fonts you can use for your thumbnails for maximum impact! Apparently others felt this list was a very good one and vouched for fonts listed here in their own thumbnails.

Futura Bold

Bebas Neue

Oswald Semi Bold

Open Sans

Compacta

Champion Lightweight

Helvetica Bold

Museo Sans

Poppins

Roboto

Lato

Noto Sans

Playfair Display

Gilda Display

Pacifico

Satisfy

Kalam

Courgette

DM Serif Display

Teko

While not listed here, I personally use Bangers font because it is still a bold font that looks great big or small and I felt like it has a bit of personality that works with my branding.

I hope this helps!