I suppose my pet peeve (when I beta read and edited) was to work with an author who requested feedback... but didn't truly want any. I don't expect a writer to implement every content edit I suggested. I do, however, expect them to, at least, consider those suggestions. Or pretend to consider them.
There is a fine line between mechanics, art and ego. Don't ask for an editor if all you want is a cheerleader.
"Said" is largely invisible to the reader. It should be your default dialogue tag, especially when there are several people speaking. "Said" allows the dialogue itself to do the heavy lifting. However, as discussed above, I eliminate it when possible. Superfluous is superfluous. 😉
I can be horrible at word/phrase repetition, especially if the segment in question was penned in one session. Depending on the day, certain words and phrases stick in my head and sneak into my writing over and over again. Time is your best friend here. Step back from completed chapters/stories for several weeks, then reread. That's when you catch these things.