I’ve actually got some of them, they’re a fantastic brand and very high quality. However I don’t like the extra stack height it adds for the spd so ones. Those are the speedplay extenders I’ve got.
I’m wondering about taking a Dremel to the bottom of my shoes but this feels pretty…extreme.
Both are great choices, and come down to the all too common choice of ‘weight’. There are other benefits, but the easiest is weight. I’ve had both on outdoor bikes and smart bikes and would be hard to tell the difference. I prefer the Ultegra for the road bikes because they are full Ultegra,and for no other reason (not a racer).
The Ultegra has a shorter stack height.
Here’s the Dealer Manual from Shimano on those pedals.
Saw Dura Ace pedals for $280.00 last week. 
I’m still riding a set of Looks from 2008. Fine pedals and no reason to change, though I do have newer sets too, and Shimano SPDs. FWIW: they and their design predated Shimano, which is bit of a knockoff of them. Imitation is the sincerest form of flattery.
First doesn’t mean best. Particularly in this case since the Shimano design wins in the walkable category that also lead to better cleat longevity. I’ve also seen more than a few sets of Look pedal bodies dead from wear due to their insufficient wear plates. Look is fine, but Shimano is better from my experience and preference.
Even if my life depended on it I would be able to tell the difference between look and spd-sl, not clipping in/out nor walking (on the grey look cleats, there are also other look compatible cleats which are much slippier)
This is going to sound like the most “herd mentality” comment ever, but the thing is that, every person I know that veered off Shimano pedals was eventually back to them within 1 or 2 years.
Not sexy, but they just work. Ultegra is the sweet spot for me, at least with European prices. Light enough, good platform, durable and 2 axle length options. 105, if my memory serves me well, is only marginally cheaper, a bit heavier, thicker stack and only 1 axle option
I too hate look cleats. I moved to shimano cause I got tired of wearing them out in less than a year, and I ride the/my mtb way more than the/my road bike.
On top of everything already mentioned, Shimano pedals have their balance just in the right place to maks it easier to clip in.
I’ve used them all (except Keywin).
Shimano are my overall recommendation - most reliable, easy to get and a very functional cleat. Float is 6 degrees with yellow and it has a bit of lateral float on the yellow cleats only.
Look - I had the new carbon blade ceramics - Look the best but are prone to scratches. Come with a 4.5 or 9 degree float cleat but do NOT have lateral float. Some people prefer this, I absolutely hate it. Spindle can take a bigger washer to adjust Q factor more than Shimano.
Speedplay - I am not a fan of the Wahoo rebrand, the pedals seem to develop play a lot more. Great for float and aero, I found them the hardest to clip in of all the pedals, difficult to set up and they don’t have lateral float.
Time - my preferred pedal feeling wise, 10 degree float and 2.5 mm lateral float. Mild self-centering feeling which I like as it makes the float feel less loose. Worst build quality and bearings. Not tried the rebranded Sram ones though so hopefully they are better.