Personally what has worked for me up to now is to send them to both at once.
Heres how I do it...

I will have a small drop down pop-up opt in form demonstrating a free bonus gift RRP $x on my sales page.
For signing up to the newsletter and then then have the opion of closing the box and carry on reading the sales page so you kinda kill two birds with one stone.

So rather than a squeeze page I use a squeeze box and I still get a load of sign ups because I always redirect them back to the sales page once they've opted in.

It certainly works for me anyway but I guess it depends on your niche, I guess you gotta play around with it and see what suits you best.