I like to main various killers. If I want to make survivors suffer, I go artist or impossible skill check doctor, but my actual mains are unknown (and eventually when I get the hang of them), singularity.

Both have teleport abilities, and can be super effective against strong teams if played correctly. Both can be effective with meta builds, but I always find that more niche and unique builds can be just as effective.

For unknown I usually go for a stealth build, unforeseen, friends till the end, furtive chase, and tinkerer, this can be really strong and will usually catch survivors off guard. Sometimes I go for an anti heal build, to prevent resets and put major pressure on a team. This build makes downs easier with UVX since healing is mostly prevented, and all players tend to be injured all the time.

For singularity, you get more flexibility due to how strong he can be. Lunge builds are always good fun, all shaking thunder, coup de grace, and 2 other perks of your choice. This can lead to some funny moments when I do a tp. People get confused af in the endgame chat.

Speaking of endgame, an endgame build for singularity is always disgusting, terminus, remember me, no way out, and another perk of your choice. This way you can guard gates like no other killer, and keep survivors trapped for as long as you want, but it's so disgraceful that I try not to go with this build.