It's a shame you had such a bad experience in the store you went to. As someone who may have or may know of a person that filled the shoes of the store employees in the past (at least corporate stores) I want to clarify a few things for the people here about how things work at the store in these situations.
Rep Knowledge
First of all, the reps are going to be limited in experience on what phones get "good reception" by a few factors:
1. they carry the phone themselves as a demo device (which they can change every 3-6 months) so they use it so know how good/bad reception, camera or similar features are.
2. they have had customers come in with (or without) problems with the phone and tend to build their opinion from that.
Reps have access to forums internally where they can read about "if" an issue is a known issue but because so much time is spent troubleshooting (and they are usually sales reps who want to sell something to keep their job) they don't really take the time to bother posting issues to begin with rendering the forums useless many times.
Reps are never trained or told what phones work better, like life it comes from experience and the phone that walks in the door with the most problems taking them away from selling for 30 minutes while they troubleshoot will be the phone they don't want to sell again. Keep in mind, this is because the company has gotten rid of store technicians and many have no customer service people and everyone has to hit goals to make money or keep their job. This is not the sales reps fault, but if you notice their manager is probably breathing down their neck to hurry up and get to the next customer if the store is busy. You may get lucky and get the more techie person (as I call them) who may be a phone geek and does read up and do research so look for that person in the store or call and say 'hey, who is your most tech savvy rep there, I have a question' and see if you get lucky. Customers did that for the person I knew all of the time because they were definitely a phone nerd and tended to carry more than one device and knew them well.
Going to the store for help with a problem during your 14 day return period
Next and more important thing to remember when you come in during the 14 day return period is that you sounded the big alarm walking in with that box or bag. Reps HATE returns as it hurts their pay and can cost them their job for not showing you the right device the first time. Also, it is EXTREMELY difficult to have to swap a new phone for another one for any reason. In the area I am familiar with they went so far as to set up a special call center to call in to just to force reps to do full factory resets, and many other steps (this takes a LONG time people) just to prove it is actually the phone that is the culprit. They did this to lower return rate. (remember, we are working with a for-proift company that bases things on many metrics including returns of new devices being a huge loss)
With a reception issue, it is always going to end up becoming a troubleshoot first, call troubleshooting line, check forums and internal memos, then swap SIM, note account, have customer try again, then go through same steps including many times calling tech support for network troubleshooting before you can pull a new phone off the shelf and swap it.
IF THE REP SWAPS THE PHONE - it always has to be for same device first time (w/o manager approval, which depending on area and their return rate may or may not be easy to do). This takes more time, the POS system doesn't always cooperate and is not what they want you to do but sometimes has to be done. The 3rd phone can be a different model but at least when I was familiar with things, this then went against our return rate % which actually hurt the originally selling reps paycheck and them us on a "list".
The rep is paid more or given incentive to push a certain device
The short answer: absolutely not true.
The most ever given out from what I know during many years is a free coffee mug, coozie, water bottle or some other cheap giveaway when the rep from a manufacturer would visit (which was rare and only a few manufacturers actually sent them to stores anymore). The compensation plan doesn't discriminate against or promote LG, Motorola, Droid, or any other brand or manufacturer at all and there is no reason to push a device unless it is free and they are trying to get you add-a-line or something but that is to get you to buy a service not a device. The only reason a rep would push you to a device is really because they like it, they are more familiar (and therefore less intimidated by selling it) or even more likely, have found it to have lower return rate. I doubt they were trying to lead you the wrong way, they are human too and just have to go by life experience, not fancy corporate specs and features because what they are given is the same thing you find on the Verizon web site.
By the way, the location of phones in the store is decided by corporate and all are the same layout in most cases unless a manager decides to think outside the planogram for some reason.
Hope this informs or helps someone and since I was here doing my research on important things I am considering for my next phone you can safely guess this is how I decide which one I will get next.