6" or 8" options
Care level- Medium
These are labeled as more dificult to care for because there really isn't a one size fits all care guide, and you will have to monitor the plant in your space and adjust accordingly. For light, start with a middle-of-the-road approach of a few hours of direct light a day. If its leaves begin to turn to all green with the lowest ones dropping, they aren’t receiving enough light, and you might want to move the plant to a south-facing window instead. If the foliage takes on a grayish bleached look or its yellow sections turn black, the plant is receiving too much sun, and you can move it or add a sheer curtain between it and the glass.
The croton plant requires frequent watering, but be sure not to over-water. Too much water can cause root rot, but too little water can dry the humidity-loving plant out. You can use the leaves as an indicator of water needs, as it will begin to wilt when thirsty. You're looking for a moist, but not constantly wet balance. 
Overall, this plant is a bit picky, but the awesome colors and patterns make the effort well worth it, and once you find a spot and routine that works with your plant, its easy peasy maintenance from there!