For Mac, you can use Photos app or AriDrop.
Photos app will allow you to download camera roll photos
1. Connect your iPhone to computer > Open Photos.
2. Click on Import option > Select the pictures you want to download.
3. Click on Import XXX Selected. Or you can choose Import All New Items.
AirDrop
1. Enable Wi-Fi and bluetooth on your iPhone and Mac. Open AirDrop of course.
2. Go to Photos app on your iPhone > Select the photos you need > Tap on Share button > Tap your Mac name.
3. Confirm the sharing on your Mac.
For Windows, you can use AutoPlay.
1. Connect your iPhone to computer, and the AutoPlay will pop up automatically.
2. Click on Import pictures and videos to download iPhone camera roll pictures to computer.