Jive's Technical Support Team
The best aspect of Jive is their 24/7 support team. When you have issues with your phones, immediate support is a must have and you get that with Jive. There Technicians are able to remotely access your computer in a support environment and this allows them to really assess the ongoing issues.
The second aspect of Jive that I think should be highlighted is that you get all kinds of features at the standard price and you're not nickle and dimed. If you really want to get the most out of a phone system, Jive allows you to do that without picking up additional costs. There are a lot of platforms with a small upfront price but by the time you have setup your PBX you have doubled your bill because you used basic features like Auto Attendants and Virtual Faxes.
Integrations is also something that Jive seems eager to assist with. Even with cases where they don't have a known integration, their support team will often work with whatever integration you're interested in to see if they can make it happen!
Jive is arguably the simplest PBX I have worked in.
I also find a lot of value in the ease of which you can order new Phone numbers and then track the stats of those numbers. You could manage the efficiency of dozens of marketing programs at once at virtually no cost. Exact information as to how many people called based off of your promoted number. Review collected by and hosted on G2.com.