Personally, i would go for the 5907.
I also like the saphire back with the power reserve - the power reserve on the back is a neat idea and quite an extra. So you have both, a classic dial and the nice movement with power reserve on the back.
Another thing to consder is whether you prefer an automatic over a HW version. For me, i would not mind a HW version - i have a few watches that i have to wind and it is a acutally a pleasure to me.
There is no right or wrong choice here so just go for whatever catches your heart.
Stefan