It's always hard to tell shades of colour from uncalibrated photos on an uncalibrated monitor. My preference would be for a shade in between red and orange. Not pure red, but not bright orange either – one of the last shades of orange before it becomes red. Gives it a fiery glow.
By the way, for showing photos of red, you should save the JPEG images with chroma subsampling off (1:1:1 or 4:4:4), otherwise red goes very smeary, blocky and washed out, which is happening in the red-on-grey keycap photos. IrfanView can certainly do this, as can GraphicConverter; Photoshop typically could not, but maybe Adobe have implemented that now. (I still don't know why red is so badly affected by subsampling.)