Looking for the most diabolical and disgraceful faction.

Hello all! I have three brothers that are very big into Warhammer 40K. Two of which have recently picked up the hobby over the last 5-6 years and one that closet collected for almost 10-11 years now. They have also convinced my boyfriend to join and he’s now collecting Custodes. They played their first tabletop together over the recent Christmas and it was pretty awesome to watch. My sister in law and I love to give them a hard time about them geeking out over it. All in all, we love watching them get excited and so immersed into the game and thought it would be fun to closet collect on the side for awhile and be able to surprise them one day and maybe play with them in the future. We just know that they will absolutely soil their britches when they find out.

We are looking for opinions on what some of you consider to be the most diabolical and disgraceful factions. We have full intention to go hardcore girl power on the painting. We both have been doing some research on the side and thought it would be a good idea to post here as well!

I’m not sure if any of this information is necessary but my brothers collect the Space Marines, Tyranids, and the T’au Empire.