In regular Mathematica one would normally use Input cells.
Code cells are used in package.m files. They contain the code for the routines, not Input cells. You can switch between the two cell types by selecting the right hand cell bracket and using Alt+8 (for Code) or Alt+9 (for Input}. Old inactive code can be saved as Input cells in packages. It is sometimes useful to swtich package usage Code cell to Input for editing. I find that switching from Code to Input cells for editing regular code is a problem. Maybe it's the disparity in AutoIndent. But one can use Returns and spaces to pretty print Code cells and maybe higher magnification.
Also remember that one can use Title, Section and Text cells in package files so they can be well organized and formatted.