I can't comment on the other issues, but a slide-out keyboard is hard to beat.
The Droid 4 has a 4.3 inch display with a screen resolution of 940 x 540.
The Samsung S3 has a 4.8 inch display with a screen resolution of 1280 x 720.
Virtual keyboards almost always occupy half of the available screen real estate. That means that when the Samsung S3 has the virtual keyboard displayed, the available screen resolution is only 1280 x 360 (or 640 x 720), either of which is 460,800 pixels. Because the Droid has the slide-out keyboard, however, its resolution remains 940 x 540 when you are using the keyboard, which is 507,600 pixels. That means that the Droid 4's screen is 10% bigger than the Samsung S3's when you are using the keyboard. Add to that the remarkable speed of the Droid's mechanical keyboard over the Samsung's virtual keyboard, and the Droid 4 wins by a country mile for texting or internet use.
Of course, this assumes you will use the phone for internet surfing and texting, which perhaps you will not. But is that not the primary reason for buying a smartphone in the first place?