We live in a rural area at a location more or less equidistant from three TELUS towers; the closest is 10km away. My wife's old Motorola W385 (CDMA) flipper is excellent as is our son's Motorola Defy. Both phones never drop a call and seem to always connect no matter where we are. Over the years between work and personal use, I have had Samsung, HTC, Apple, Blackberry, and Motorola phones. My current phone is a Motorola X Play. My daughter has a 5S. At home the X always connects when placing a call, never sits on "sending" a text message, and does not seem to miss any incoming calls even though it seldom has more than one bar. Blackberrys were excellent but all of the other phones have been hit or miss. Nothing is as frustrating as walking around holding a phone in various positions just to get a text message to go. iPhones have been quite bad although the 5S seems to be an improvement. I do not have any experience with the latest iPhones and Samsungs. What experiences have you had?
Flip phones have a fairly large antenna, compared to most smart phones, so your experience is no surprise. Use of a phone in any fringe area can be hit or miss. Some folks use a signal booster to overcome this problem.
You might speak to a supplier about testing a number of phones at your location, or check the option of Telus Extend, to see if Wi-Fi calling and texting would be an option for you.
I have an iPhone and my experience is the same. In fact, when I drop to one bar of signal (especially when it's one bar of 3G), it almost always drops completely to "no service". What's interesting is that when I was with Rogers (also on iPhone), my experience was completely different. Even in places with one bar of signal on Rogers, data would still connect and be relatively quick, and calls would work perfectly with no "feeling" that they would ever drop. Goes to show that it's not entirely device dependent. The network has a lot to do with it too. I would say it's a combo of both.