I never realized this until I kissed someone with thin lips. Ew haha I know that sounds bad but damnn... Now if i do date someone, they need to have thick or medium size lips at least... Kissing is an art and someone with nice, luscious lips... DAMN... you can kiss for days! And not only that, then the kisses are nicer and not sloppy and all wet, like with thin lips because they have to use saliva and tongue to kiss... it just gets messy and eww... I really hate it/that. So plump kisses for me all the way haha and sorry for those men or girls with thin lips... It's better to stick with thin lips because once you taste those nice medium size or thick lips that you just want to bite... you'll never want to stop sucking or getting enough of them! Those are best. #handsdown haha :p I have medium sized lips.
If (based on the pictures) that's plump and that's thin, I'd say mine's somewhere in the middle, tho leaning a bit more towards the plump side. And I love it when he sucks on them or nibbles them a little whenever we kiss... mmmm