I also play a male Tav, he's a bit taller than Astarion (around +5cm) but it's like they're almost the same height honestly. I never knew the angle was better with a taller character (because I always play with the same character, I'm too attached to him). Thanks for sharing !
It seems the angle I have in my game mostly looks like the third pic you posted in your 1st spoiler tag, it's kinda ok, but I totally get it can be weird for smaller character (2nd spoiler tag).
Also, improving the angle in general would be nice. Now that I see all of this, I adore the second picture's angle, you actually see their faces, when I always only have Astarion's back in my game and just a part of my Tav's face (if only we had a free camera ;_;)