One that I frequently trip up on is accommodate. In fact I misspelled it when I just typed it! I always forget the second “m”. It’s like I have a mind block on it.

Ditto for me. I can’t spell accommodate correctly without the help of a spellchecker.

My other fault, which may be unique to me, is that I continually type they’re for there or their. With most people, it’s the other way around.

coughs discreetly

I’d have said the most commonly misspelt are there/their, whose/who’s, where/were/we’re.  You could argue that they are the most commonly confused instead of most commonly misspelt, but the confusion leads to spelling mistakes.

Dave, just call to mind a cognate. I’m sure you have no problem with commodity. Remember that and you’ll never hesitate over accommodate again.