I would go in 14A and this is where I generally travel. Although the UD is more quiet I find it can get too warm.

14A is just as private just like 64K both have direct aisle access

If you are going to go upstairs I would go for 62K, its a bit cooler as its next to the emergency exit and you can also have the crack with the crew that sit in front of you. The UD does have the side bins for the window seats which you prove very useful

Theres no right or wrong here its all personal preferance.