Kill Team is easy to set up due to low model count but not so easy to play in my opinion. The rules are a lot more complicated than
40k and game lengths are comparable (for me at least
)
If you're interested in card games like Yu-Gi-Oh/Magic the Gathering,
GW have developed their own hybrid board/deck building game called
Warhammer Underworlds. I've only played it once and it's not for me, so I can't really give a fair assessment of its difficulty.