Skip the 4k, his budget is way to small and he'd need a monster PC and storage to handle the footage.
Not necessarily so. I'm using the GH4 and so far I've been recording in C4K, editing in 4K (did have to upgrade software...$89.95 cost), and rendering to 1080p. Computer is an HP with 2nd gen Core i7 processor. Healthy but not a "monster" PC.
For storage I was already using a pair of 2TB externals with a 3rd as "standby" if needed.
I suggested the canon 70d because of its AF system is like that of a regular video camera. No fiddling with focus rings.
That is an outstanding camera but "continuous autofocus", while seemingly better than others, can lead to disaster if you're working in an environment with a background having lots of contrast. Continuous autofocus begins "pumping" back and forth between subject and background. Doesn't "track" as good as camcorders.
With 4k comes extra issues. You need a ton of storage space, fast storage medium/external record deck and a very heavily built PC to edit the whole thing.
Storage space: You should already have that "ton", I'm not having that issue
Fast storage media: Standard 7200RPM external drives are doing fine.
External recording deck: Not necessary, 4K recording on my 95Mbps SDHC cards works fine
Very heavily built PC: For 1080p he should already be using something with a quad core fast clock speed processor and a decent graphics card.
Stick with HD until you can afford all the extras that come along with it. I doubt the OP even has a 4k monitor.
Nor do I have a 4K monitor, and I'm definitely going to wait on the 4K TVs until prices come down A LOT!. So what am I doing with 4K?
Video filmed in 4K, edited in 4K, then rendered to a 1080p file (I usually render to an MP4 as that is "cross platform") displayed on a 1080p TV looks a bit better than 1080p from other sources. Image tones and tonal details look better, delivery to others is often on a "thumb" drive.
My opinions are from first hand experience. I have the camera and am learning some of the ins and outs. A GH4 owner does not have to shoot 4K, there are other options and reports from the field indicate shooting in 1080p with this camera still seems to result in slightly better looking footage than with previous models.
One of the big improvements over the GH3 was in the EVF which is brighter, sharper definition, and much easier to see focus with.