I often preferred casting Preordain in Pauper when I played Mono U Delver years ago. Seeing up to 4 cards with Ponder seems really nice when trying to combo, was good when i needed to hit a land or something v specific and gets significantly better with fetches. Only Legacy experience I have is with DnT and BUG Leovold. I played a couple Ponder in BUG, but mainly relied on Brainstorm. Didn't often get the same bad feels when i wanted one of the top 3 then having to draw the rest.
Thinking about the sequencing in Storm when going off, Visions -> Sleight, you might want to scry both to the top, but then you can't get both with Sleight. You also see 3-5 cards, but Sleight -> Visions you always see 5 and set up your next draw if you whiff? Tho seeing 3 vs 5 seems a moot point if you're getting the cards you want... With either sleight or opt, you have a higher hit rate if you need to hit gas now and aren't chaining cantrips together.
Visions and Preordain seem closer to equivalent as setup cards t1 or 2, with Preordain being a significant improvement on the turn you go off. It doesn't seem close to being a significant enough change to take Storm from Tier2/1.5 to 1 or 0 though. Interesting to think about anyway. I appreciate and have enjoyed having Opt in the format. A decent 1cmc instant cantrip (that isn't restrictive like thoughtscour), nice to snap back, easy to keep up, but casting Serum Visions is still so painful at times :'(
