NEX-5N or NEX-F3 for expecting father

I would go with the NEX-F3. Especially for a baby, I think the built-in flash is a big deal … it's just always there if you need it. Those "moments" with a baby can pass in a flash, so don't let the lack of one keep you from catching it.

ISO 25,600 is over rated, so the max of 16,000 on the F3 shouldn't be a limiting factor.

The screen tilting up 180 degrees so you can see it from the front will be great for those quick, informal family portraits.

as it explained by snapsort here,  the different between both are touch screen and built in flash and the rest of the features are almost identical. but for those who didnt know that, sony nex 5n does comes with external flash which can be attached using the smart acces port on top of the body of 5n. i have 5n my self and have using it for 2 months now. so far im really happy and most of the time be amazed  by the image quality, and often i found the pics quality from my 5n are comparable or if not, better than my other camera which is canon 60d(5n using 18-55mm and canon using ef-s 18-135mm) but once again lens is the big factor in producing good quality image thoo.. theres only one thing that i kinda hate from 5n, you cant take self portrait as it wont let you tilt the screen like f3 does. but overal.. i may say its the best compact mirrorless camera on the market today. get one!

I would go with the NEX-F3 because it has a built in flash, and you do not have to bother with attachments. 

Both excellent choices, but I recommend the NEX-5N. Both of these cameras are excellent low-light performers so I think the built-in flash is hihgly overrated feature. Using the burst mode (which is better in the 5N) you get way better results than using a flash.