Ones i like
rasputina,
4 hoarcat prides,
sabertusk
wendigo
or
Ramos
6 steam arachnids ( if you want 3 or 6 in a swarm its fine also)
brass arachnid
steamborg ( I love the moddle and your oppents to dent to concentrate on killing it. but if you want more SS or prefer joss you can take him.)
I dont know about marcus as i have not played with him.