Is one adjustable stem better than another or is it all the same?
That sounds like a trick question 
.
I’d definitely go with one that’s adjustable in metric increments.
I think the Look adjustable stem have the most adjustability and of course cost the most too.
Some adjustable stems are more adjustable than other adjustable stems, it all depends on the adjustability of the adjustable stem, capiche?
Look – infinitely adjustable in both reach and height. Solidly built, very nice thing to have. ~400 grams. The Look stays put via tight bolts and friction. Grease the bolts so you can get it tight. Mine has never slipped.
ITM – only swings up and down, so has more limited range. For example, as you raise it from its lowest position, it also moves the bars farther away from you. As you get it up past horizontal, the bars start coming back to you. Available in two lengths to help make up for that. It’s advertised as swinging up to 45 degrees (or 135 if you measure that way), but actually goes another 15 degrees farther. If you apply a file to a little metal stop, you can get it to go yet another 15 degrees and still be soundly bolted together. The ITM stays put via a big bolt, PLUS another little bolt off to the side that both locks the stem in place AND locks the big bolt in place. It’s impossible for this stem to slip. Only ~200 grams.
I have the ITM installed on my tri bike. I filed down the metal stop so that it points almost straight down at the ground.
Ritchey – works the same as ITM, but doesn’t swing up and down over as far a range. This stem stays put via tight bolt tension and little grooves that hold the stem in place. I haven’t fooled with one, but it looks like a safe design.
Does all that answer your question?