I'd wait for h370 motherboards in a few months before considering Coffee Lake for a 'budget' build.
NVMe and USB3.1 may sound nice but under most real-world consumer circumstances, NVMe has very little benefit over SATA3. Likewise for USB3.1. Nice to have just in case if you can get them at little to no added cost, but not deal-breakers for most practical uses - tons of people still use PCs much older than either standard and have still have no plan to upgrade in the foreseeable future.
If my i5-3470 exploded today and I needed to get a new PC up in a hurry on a low budget, I'd probably go R3-1200 with a B350 motherboard. Otherwise, I'm not planning to upgrade until Ryzen 2/3 or Icelake in 2019.