honestly, it depends for me...
usually subs have better voice acting (makes sense, as the anime voice acting industry is much bigger in japan), and especially with more serious and emotional anime dubs can take me out of it due to goofy voices.
however, for things more focused on comedy, i honestly think dubs are often better. subs, i find, often try very hard to be "accurate", which can sometimes seem unnatural, and with comedy, the timing and structure of a joke is often lost in translation. however, since dubs have a higher level of localisation, and need to sound natural to some extent, often comedy just flows better. for example, take saiki k. i honestly think that anime is funnier in dub, which is partly due to the fact it doesn't try super hard to be an exact translation.
although, since i'm learning japanese, i usually just watch in japanese with japanese subs
