Well you don't say what your price range is. So I will give you some suggestions:
Laser: Epson LS10500
I've not seen this projector in person, but word of mouth is that it is a very good unit. MSRP is $8k, but I'm sure you could get it for less. It's an panel shifting 4K unit which means it uses a 1080 panel and shifts it show more of the 4K picture information than a 2K projector. Sky is the limit the high end lasers from Sony and JVC are amazing, but I'm guessing $20K+ isn't what you're looking for.
Bulb: JVC RS520 or RS420
I've seen several examples of JVC's RS5x0 and RS4x0 projectors. The 520 throws the second best picture I've seen in person (it's bigger brother the RS6x0 family is the best). Street pricing is going to be in the $4-5K range for the RS520. The RS420 is going to be bit cheaper (~$3-4K). It has less 4K BT202 color coverage (~70% vs ~98% for the RS5x0/6x0). It also lacks the dual iris system of the upper range models as well, so it has a higher black floor and less contrast. But it's still stunning and my choice if your budget can't stretch far enough for an RS520. Both units again use panel shifting to display 4K information.
There are other choices. The Sony native 4K units throw a very nice picture. The one I saw could not match the picture of the JVC RS520 despite a higher cost. The native 4K panel is very nice, but the panel shift techniques used by JVC are good enough that I don't consider it enough to offset the better overall picture the JVC offers.
Another choice would be the Epson 5040 UB (or 6040 UB). I've gotten to see a couple of these. They are very nice units, but the black floor and contrast are not close to what the JVC RS420 offers. Also the JVC RS4x0 lenses I've seen are much sharper than what the Epson offers. If you can't stretch to reach the low end JVC this isn't a bad choice, but I would certainly try to get the JVC.