We switched from AT&T to Verizon years ago because my friends with Verizon were making calls in places I could not with AT&T. Not sure if AT&T got any better since then.
As far as a phone that is up to your personal preference. If you get a smart phone you can use it as a hot spot and then tie in your wireless devices such as a laptop, notebook or ipad. If you already have a ipad you may want a iphone as they are similar on how they operate. If you do plan on using the phone as a hotspot make sure the new phone has 4G for faster internet speeds.