Inkscape is pretty full featured, free. I found it to be a steep learning curve. Keep in mind, I'm no graphic artist, I'm a programmer who has learned a little about how to design icons, and learned a whole lot about how to manipulate SVG files (they are XML). I felt more comfortable with a tool that reminded me more of Paint. On macOS, I liked iVinci Express, it has a really simple clean interface. I have not used it, but Vectr.com looks very easy to use. We also package a fair number of extra icons with SlickEdit that you might just be able to use out-of-the-box (Tools > Options... > Appearance > Toolbar Customization... > User Definable Tools). There are also toolbar buttons for many other SlickEdit builtin commands in the other categories.