There's some confusion about what HDR is and what would be the best solution for it.
HDR video usually has several separate components:
It's usually 4K.
4K on 3LCD (Epson) and some older JVC's have ~4m (addressable) pixels (1080p has ~2m). Native 4K and DLP 4K have ~8m pixels.
Besides pixel count, lens quality also matter. For instance, Epson HC4xxx and 5xxx/6xxxUB series have better lenses than the Benq HT3550/TK850. The 4K Optomas also have better lenses than the Benq. The issue of what is the sharpest type of device is not settled, there is a debate over what appears sharper, with different opinions.
The source is also relevant. Most movies have been shot in 2K and repacked as 4K. There is a difference between those shot in 4K. Only around 80 titles have been shot in 4K, excluding TV. Upscaled 1080p sources can also be an improvement over 1080p.
Contrast is known to increase sharpness perception.
Wide Color Gamut/WCG.
This is an expanded color gamut, that is sometimes measured in DCI P3, Rec.2020, or as a positive to Rec.709. The HT3050 covers ~ 100% of Rec.709, or ~71% of DCI P3.
Calibration and projector preset affect color accuracy.
The 4K Optoma's can cover ~80% of DCI P3, The Epson HC3800 between 71-75% (with calibration), Benq HT3550/TK850 ~85%, Epson HC4xxx and 5xxx/6xxxUB ~87%.
The HT3550 and Epson HC4xxx and 5xxx/6xxxUB series can expand coverage to 100% or more via a filter. This filter reduces brightness by 30-40% on the HT3550 and 50% on the three Epson series mentioned earlier. The others don't have a filter.
Considering the screen is 140" AT the HT3550 is much to dim to be used with a filter.
For instance with the Epson 5050UB (and HC4xxx series) mounted closest to the screen Bright Cinema (with filter) on Eco has ~1400 lumens. Half would be 700. If the HT3050 is bright enough than so will the Epsons be.
Many users don't use the filter on the Epsons for this reason since it covers some part of the DCI P3 gamut and they prefer the brightness to covering the rest of the gamut.
Not exactly sure how much the filter takes from older JVC, the ones that have it.
For the expanded color gamut and grading it was considered that a display that can display more grading will be better. 1080p with 256, while 4K with 1024.
As it's mentioned above, some projectors like the 5040UB only have a 10GB HDMI which limits the bandwidth so that 4K HDR 60Hz 10bit is too much. The bit depth needs to be dropped to 8bit to fit in the 10GB bandwidth. Dropping the bit depth will make the image more susceptible to banding, however haven't seen any reports.
had a 10GB Epson projector with a HDFury linker, maybe he can provide more details.
SDR video is mastered to 100nits in the 0-256 range, with 16 being black and 235 white. HDR is mastered to 1000/4000 nits or higher 0 being black and 1024 being white (or something like that). Obviously projectors can't reach this nit value, average around 100 nits. Each manufacturer has it's own algorithm for tone mapping the HDR video to what the projector can actually do. This is a new feature on projectors and results can vary in quality. External boxes like the Panasonic can also do that.
These four components don't have to be linked together. For instance 1080p with WCG exists, 4K without WCG and mastered to 100 nits also exists, etc.
Having said ALL that, the other components for what makes an image look best still apply. Arguably the most important is contrast and black level. While people are different and may like different things, generally speaking an image with proper black level, good colors, is what would be pleasing to most.
A projector like the 5040UB or a used JVC that have good blacks (especially the JVC) and colors will be superior to any of the DLP mentioned above. Even if some JVC models don't have 4K or WCG, they will still produce a better image than the latest 4K DLP's. The Panasonic will convert the image to the appropriate resolution and color gamut.
The projector with the best image should be selected, not the latest iteration with "features" that still don't match good quality projectors.
The UHD51/52ALV or TK850 are living room projectors for ambient light, not dark room projectors. They sacrifice everything for brightness. If you want to purposefully buy an inferior product than go with any of the DLP mentioned above.