There is no ideal 4K projector, certainly not at a reasonable price. So you will need to decide what trade-offs you can accept. The new Sony VPL-VW385 appears to offer most of the performance and features of the VW675 that was introduced a year earlier. So you get native 4K resolution, HDR support, lens memory and a dynamic iris for better contrast than the entry level VW285. These Sony models use a lamp-based light engine. They are limited by a HDMI 2.0 input that only supports 13.5 Gbps max. input data rate which is short the 18 Gbps allowed by the HDMI 2.0 standard. As a result the available performance for using with 2160p @60Hz video sources will be more limited.. This is not a real issue today for use with Ultra HD Blu-ray discs. The price is $8K. Other under $15K projectors all use pixel shifting to provide 4K-lite or pseudo 4K support..
The JVC lamp based models use pixel shifting with 1080p display chips which means they cannot display display the full 4K resolution but they do appear more detailed than a regular 1080p projector. In fact the difference in visible details in their displayed image and that of true 4K projector is rather subtle with the vast majority of video material on UHD Blu-ray or 4K streaming video. The JVC's, such as the DLA-RS540 ($6K list), or the more expensive RS640 ($8K), do support a wide color gamut (out to DCI-P3) and have industry leading contrast/black levels and have full bandwidth HDMI 2.0 inputs, so they are good to go with all current 2160p @ 60Hz formats support by that HDMI standard. Also be aware the JVC's are allowed to be discounted while the Sony's are not, so the flagship JVC pixel shifter RS600 will have street price will under that of the Sony VW385, even though their list price is similar.
Epson has their LS10500 carried over from last year and it does have a laser light engine and uses pixel shifting along with 1080p display chips, similar approach to that used by JVC. Its light output is lower than the JVC RS500/600 when the JVC has a new or low hours lamp, but the Epson's laser should retain it brightness for a very long time with traditional lamps frequently lose 25% or their original brightness by around 1000 hours of wear on the lamp. Its HDMI 2.0 input does not support the full 18 Gbps data rates so it compatibility with 2160p @ 60Hz formats is limited.
The new DLP 4K projectors also use pixel shifting, but instead of the 1080p chips used by JVC and Epson (with 2 Mpixels each), the DLP uses 4 Mpixel display chips so there image will potentially be a little more detailed then the JVC and Epson pixel shifters, but still a little less than a native 4K Sonys. Note there are other factors at play here since the lens quality and the alignment of the red/blue/green panels in the Sony/Epson/JVC can also visible impact resolution. Also these DLP single chip projector are subject to color separation artifacts, better know as rainbow effect, that some people are sensitive to. I am in the process of reviewing an Acer 4K DLP and I can occasionally see the rainbows, but you might not. The basic 4K DLP models from such companies as Acer, BenQ and Optoma are selling for under $2.5K with the laser models start at under $5K. The entry level models tend to be short on features (e.g., manual focus, manual zoom, no lens memory, etc) and also only display Rec. 709 color space even though they may accept inputs in the wide color spaces used with most/many UHD video sources. Also these 4K DLP models have rather low, by todays home theater projector standards, contrast ratio with higher than ideal black levels. Note that manufacturer's specs. for contrast ratio are meaningless in most cases (JVC is an exception). For example, the Acer I am reviewing measures at under 1500:1 native contrast ratio, as it would be operated in the real world, while the Acer spec. sheets say it has a CR of 1,200.000:1 (I guess that was measured with the projector's lamp turned off for the black measurement).
You may want to check out some of the reviews and articles we have published at
www.projectorreviews.com (but reviews for some of the very latest models are still to be published).