However I do not like middle section that is too straight after those nice bends
I think the girth is just fine. The tree was apparently never maintained, so it did loose some tapering in the top.
Not much I can do about it, but personally, I think it's not really an issue. Also, it will disappear behind the foliage in the future.
Thanks for the drawings, but I do not think they are improvements.
I have considered - and discarded - the idea to only keep the lowest branch. It follows the trunk nicely, so it could work - but it's too rigorous for me. Also, I think the movement of the tree is not suitable; keeping a right branch while the trunk moves to the right will not work. I've explained this before.
Do note this is a progression, a work in progress. Of course my first concern was getting the tree healthy, to get backbudding, more and denser foliage and foliage closer to the trunk. I'm pretty surprised myself how well that worked out.
Before:
3 years later: