Hi Guys,

What are the main differences between all the pedal styles?

Right now I'm using Ultegra SPD-SL pedals. How / why do they differ from all the others? Advantages / Disadvantages?

This is a pretty good answer. No need to reinvent the wheel over here.

I ride Look; never ridden any other brand. I won't debunk any inter-brand comparisons, but the facts are wrong nonetheless. Look pedal float is not "low", it's none/low/moderate depending on which cleats you use. Walkability is poor or OK, poor if you use non-grippy cleats without cleat covers, OK with cleat covers or the newer "grippy" cleats.

For what it's worth, my third set of pedals (third bike...) doesn't feel as good as my second sent, but there's a big price difference there. And now that my wife has a set of the Look Keo Blade pedals, well, let's just say it won't be long before I buy a set of Look Keo Blades.

I have used Spedplay Light Action, Speedplay Zeros, Dura Ace Shimano SPD-SL, Look and have tried SPDs once. They all have their purposes. My favorites are the Speedplay Zeros. The SPD-SL didn't work for me, but I was new to cycling when I used so maybe I didn't give them enough time. I used them for about a month and had a hard time clipping in and out. I used the Light Action for six years and then gave them to my wife when I bought my Zeros. I use the Looks for my spin class which isn't a fair comparison.

What issue are you having with your pedals?

I ride Shimano SPD Dura Ace, Ultegra and 105 on all my bikes (8 of them), started racing back in the day on Time Criteriums.
I am just partial to them due to durability and quality. Didn't like the stack height and business of speedplay cleat system although the pedal itself is minimal.
Shimano bearing smoothness is second to none although I have come to find the price between DA and 105 is great, function is not.

different rider, different pedals...Everyone has their preference...

You are kinda picking nits there.