Buying a camera under 5k? Advice?

Hey, i'm looking to get a new video camera and i thought i'd ask for some advice. Previously I've had canon XTI, 70D, 7D, and C100. I'm looking for something new. Other than the C100, most other cameras i've had were more geared towards photography with the added capability of video. Now i'd like to transition into something that is more focused on video. I shoot documentaries, web series, and short films. That means that I do travel a lot, so size and weight is def something to take into account. Plus not all people like being on camera for docs, which means that a large camcorder may appear intimidating (it has in the past). I would like something as best as possible under the 5000$ mark. I would like to shoot 4k videos and I want the camera to have a lot of additional lenses available for purchase if need be. Does anyone have a camera that they shoot similar footage with that they'd like to recommend? Or maybe something to steer clear of? I'm not the biggest fan of Canon, even tho i've had so many of their cameras and i'm not apposed to hearing a canon recommendation, tho i'm mostly looking to branch out. I've been considering GH5 and Sony a7R. I'm open to any advice/suggestions, thanks.