Top right is the Ubuntu logo. Top green-yellow one is some African country. Bottom one in blue with three triangles is some fancy hotel brand.

Top right one looks like a Linux distro logo, so that’s pretty cool I guess

I don’t know which prefecture is attached to the flag but third row, last one to the right, the clover-like one.

Edit; it’s the Miyagi prefecture.

Third row, second column. Tau Empire.

It’s a shame that they aren’t more popular; I didn’t really see prefectural flags flown that much outside of government buildings when I lived in Japan.

These look extremely corporate, like hotel chains.

My favorites are probably the flags of and They have really appealing colors imo, and the symbols are great as well (especially Niiagata’s).