as was in that same exact case a few months ago!
I wanted to buy my first "new Patek" as all my watches were vintage.
They were vintage because I find most of the new ones too big.
I love the 5110s better than the new WTs.
I love the 3800s as much as the new Nautiluses.
I love the 5066 better than the new Aquanauts.
The point is I wanted a black dial, on grey gold or platinum, to complete my collection, because, all brands together, I had not this combo.
And I wanted a chrono.
I was hesitating between the exact same two watches !!!
I will not talk about how beautiful both are, because they are.
But the 5170g was my first choice because it seems smaller, and the manual chronograph is so cooooooooool!
And I loved the 5905p on paper, because AC + Chrono + Platinum (love the diamond) but I was pretty sure the 42mm will not fit my wrist.
And then I tried on both.
And here's the thing : the 5170 looked much bigger on my wrist than the 5905 !
So this was an obvious and very quick choice : I bought the 5905p this same day.
I regret the 5170 movement because it is gorgeous but hope to offer me a 3970 one day...
Regarding the dial, I don't really like this blue dial and love this black one. But this is really personal. They sold much more blue dials than black ones in the Geneva Salon.
I got my 5905p after 2 months and it is always a great pleasure to wear it.
I think you will not hesitate on the big day, one or the other will suits you the best and you'll be a happy man
Cheers
JC