Everyone really is going to have different opinions. It's like when you read a review on Amazon... They are all over the place. It's all personal experience.
My $.02 are this: I worked for RadioShack this past year (Yes somehow it is still open) and had to learn A LOT about the major phone companies sans T Mobile. What I can tell you is, depending on location, Verizon and AT&T have very similar reception. What some people have describes about financing the phones is called Verizon Edge and AT&T Next. Both offer you the ability to finance a brand new model (Like the iPhone 6/plus and Galaxy Note 4) without high up front costs.
Now, the way this really gets you to save is if you have the 10GB data share plan. Normally a smartphone costs $40 a month per phone, and that is before the data package. If you get Edge or Next, while on a 10GB plan, that $40 a month drops to $15 a month. You will have to finance the phone, like I mentioned, which will run you somewhere between $25-$45 a month depending on the phone and it's storage capacity.
The key here is that while your monthly bill MAY be higher (since your financing may be more that the $25 you save for getting Edge or Next) you don't have to pay any upgrade/activation fee ($40 for AT&T), nor do you have to pay that in store price for the phone (usually somewhere between $75 and $300 dollars). Therefore if you went with the 18 month plan (the most cost efficient) you would save yourself abour $100 after those 18 months.
That is the key. In order to reap the benefits you need to upgrade every 18 months, not the normal 24 months on contract. The key is, in order to do so your phone must be inspected and deemed worthy to be traded in (slight scratches and minor cosmetics aren't a big deal here) but that is why they push the insurance. If your phone take a vacation in the toilet, you cannot exchange it, or a replacement when those 18 months are up without it having been covered through the insurance.
Sprint also offers a similar plan, but I know their coverage is only really best around major cities. The reason we didn't deal with T Mobile is because their coverage was basically nonexistant in my area.
My advice is that if you think you need 10GB and would like to upgrade every 18 months, get the Edge or Next programs. They will save you some money. If money is a concern, it may be wiser to use a lower GB plan (you can still do Edge and Next, the savings just won't be as great).