They will not overwrite effects that modify power or toughness without setting it (whether from a static ability, counters, or a resolved spell or ability), nor will they overwrite effects that set power and toughness which come into existence after they resolve
P/T Number 551 Language English Legal Formats Alchemy, Brawl, Commander, Competitive Brawl, Historic, Legacy, Modern, Pioneer, Standard, Timeless, Vintage Rulings (6/6/2025) Traveling Chocobo lets you look at the top card of your library whenever you want (with one restrictionsee below), even if you don't have priority
Eventually, Wizards must have seen the pattern, and Mox Opal was banned once and for all in January 2020
Riptide Gearhulk sees the most play in Constructed 1v1 and Commander, based on the fact that its a form of blinkable removal, and it even fits as a control finisher