The "you-gotta-go-home-with-the-one-who-brought-you-to-the-dance" principle suggests sticking with %>% when using {dplyr} and friends or sticking with {base} when using |> is my take.
A challenge with _ is it can only be used exactly once in the RHS expression. For {dplyr} mutate()s, that can be limiting when wanting to mutate/create a collection of columns in a single expression.
I hear you re: sticking with {magrittr} for {tidyverse} operations, but the mixing of the two pipes feels very clunky to me. Unavoidable when using one of the 'special' pipes (e.g.%T>%), but in practice 95% of my pipes are the 'standard' variant, and I think mixing them is bad form. This 'use one pipe here but another pipe there' really adds to the challenge of introducing/teaching R to new people :-/.