Any vector graphics software will do nicely here is a partial list:
- Adobe Illustrator
- Bohemian Coding Sketch
- Corel Draw
- Xara Designer Pro
Although you may want to use a more complicated workflow where you draw in vector app and color in raster application like Photoshop. But your mileage may vary, depends what you target, web only or print only, or both.
I suggest a vector-based drawing software like Adobe Illustrator so that you won't have any problems with the size of your work as vectors are scalable without losing any quality.
I suggest that you use Adobe Illustrator and make sure that the the document color is RGB for web or CMYK for print. It can be easily export to different format later, such as PDF, PNG, JPG, in different resolution and sizes.