So one of the questions that comes up about virtualization is why you should do it in the first place. What's the business reason for it?
I equate it to planning for a garden and planting a garden.
Last November I got my shipment of tulips and daffodils from Dutch Gardens. And the bulbs are only a few inches or so in size. If you planted them just under the soil, not only would they get too leggy, but they'd not get the needed nutrition from the leaves to flower again another year. You space them out and you dig a hole for them two times their size because you know they are going to grow.
Virtualization of a server - to me - is the same process. You plan ahead that some new thing you'll want to expand, some new server, some new virtualized desktop, some new deployment is going to come along and if you haven't planned your garden - or rather your server to handle the growth, you'll have to dig it all up (redeploy it) and start over again.
Not to mention moving a virtualize server from one platform to another (Server 2008 r2 to Server 2012) or from one physical server location to another is the equivalent of moving a planted pot in my garden versus something planted directly in the soil. To move a pot is easy, to move a plant in the soil, I have to make sure I dig around the root ball and replant it carefully and monitor for any shock to the plant.
When you move a virtualized server, you only need to set up the network card and then point to the vhds and off you go. You can also do an export and import but I've honestly found it just as easy to just reset up the server in it's new home.
P.S. in case anyone is wondering, yes that is my garden with my daffodils and tulips blooming this weekend and all that hard work is pretty much done in two weekends in November. As in just like with computers, it's ordering the right parts (bulbs), deploying the technology properly (digging them in, adding a bit of bone meal), planning for growth and you just sit back and watch your clients suddenly realize that they need another server or virtual machine or something and you go "no problem, we have some spare computing power right over here on that new server we bought for you a bit back".
Whether you pick HyperV or VMware is like picking your favorite of daffodils versus tulips. Each one will do the job.