Best normal prime lens for a Canon EOS 500D?

Just as you enjoy taking portraits of your children, I have enjoyed taking photos of my daughter over the years. Thinking much like you, I wanted a quality lens for portraits and decided to get the Canon 60mm macro. As reported I found it to be excellent and very sharp. I am sure you would enjoy it.

But as nice a lens as the 60mm is, I would suggest it is really not that versatile overall to rely on it as your new " go to" quality lens. I think you would, in many situations, find it challenging to use as your primary lens. For example, at your child's next birthday party you would likely find yourself backing up into walls to try to get the shot you need inside your house (60mm on an crop sensor body is like a 96mm view on a full frame). Other than portraits over the years you will likely want to use your primary lens to get photos of your kids in many situations ...with their friends in group shots, be able to zoom in for a portrait on Christmas morning but then perhaps get a wider shot to get both children and the tree in the background, etc.

I would suggest a higher quality zoom and a speedlite for bounce flash photography indoors would be worth considering as a next purchase. I have been able to get many sharp images that, to my eye, closely rival my 60mm lens with a Canon 15-85 USM and a Sigma 17-70 Contemporary. A quality zoom will allow you to capture spontaneous moments with your kids that you will miss while trying to get into the right position with the 60mm.

As others have suggested, if you really want to go with a prime, starting with the 50mm STM would be a good choice. It is a good performer and for a reasonable price you will see if working with a prime as your main lens is right for you. Good luck!