Ok need urgent help please.

I am doing check in and I have a huge choice of seats at this moment in time and im stuck which to go for ! im looking at either right at back row 39 thinking im out of way or is that bad idea? or row 27 behind the exits seats, on the picture appears to be a bigger space between the row in front? is there more leg room? or is it not a good idea to sit behind row 26! please can someone give some good seats options like I said I have my pick! thank you. Also can I select a window seat and aisle seat and hope middle stays empty? or am I chancing that if the seat goes? and someone ends up between me and my daughter.