I am not one to recommend preordering anything but there are plenty of consumers out there that are, as you can tell by how quickly the new Ryzen processors are selling. Here is a quick look at three of the system builders offerings you can order as of today.
They offer four different systems, with all but their new Hyper Liquid model using a Corsair H60 CLC for cooling and 8GB of dual channel DDR4. All systems come with a 3-year limited warranty and lifetime tech support
Maingear is more cooling focused, with custom watercooling available in traditional soft tubing and hardline options. They also offer MAINGEAR Redline Overclocking, so your Ryzen powered system will arrive already running at higher that reference frequencies. You will pay a little more but they do put effort into the paint and aesthetics.
Origin's systems start shipping on March 12th, with NEURON, MILLENNIUM and GENESIS desktops which come with free lifetime US-based 24/7 support. They offer Variable Mounting which allows you a choice between four motherboard mounting orientations, choose the appropriate one based on your preferred cooling solution. You can also add remote controlled LEDs and in some models, up to 34 drives can be installed.
Last but not least is NCIX who not only offer several choices of custom systems but also list a wide variety of AM4 motherboards and compatible coolers for you to order individually. The lower end B350 boards look to retail around $150 while some of the high end X370 boards are over $400. The X370 above features two M.2 NVMe PCIe x4 slots with heatshields while the B350 has only one, exposed to the world.