I see that those file types can be classified in text or image files, so it'd be recommended to offer the option to select all the files of one type just with a click.

Also it provides better organization (even better if you order them by most used or alphabetically).

If the user wants to select by file type, the max amount of clicks needed is 1 so it can't get simpler from that point of view. Also checkboxes are familiar with the majority of the users and bring much less confusion compared with other options.

^{download bmml source – Wireframes created with Balsamiq Mockups}

I see that those file types can be classified as text or image files, so it'd be recommended to offer the option to select all the files of one type just with a click.

Also it provides better organization (even better if you order them by most used or alphabetically).

If the user wants to select by file type, the max amount of clicks needed is 1 so it can't get simpler from that point of view. Also checkboxes are familiar with the majority of the users and bring much less confusion compared with other options.

^{download bmml source – Wireframes created with Balsamiq Mockups}

I see that those file types can be classified in text o image files, so it would be recommend to offer the option to select all the files of one type just with a click.

Also it provides better organization (even better if you order then by most used or alphabetically  ).

If the user wants to select by file type, the max amount of clicks needed is 1 so cant't get simpler from that point of view. Also checkboxes are familiar with the majority of the users and bring much less confusion compared with other options.

^{download bmml source – Wireframes created with Balsamiq Mockups}

I see that those file types can be classified in text or image files, so it'd be recommended to offer the option to select all the files of one type just with a click.

Also it provides better organization (even better if you order them by most used or alphabetically).

If the user wants to select by file type, the max amount of clicks needed is 1 so it can't get simpler from that point of view. Also checkboxes are familiar with the majority of the users and bring much less confusion compared with other options.

^{download bmml source – Wireframes created with Balsamiq Mockups}