Recently I finished Liam's loyalty mission in Mass Effect: Andromeda, and no spoilers, the dude is utterly and completely incompetent. He also dies all the time if you pick him as a part of your fire team. If there was some way I could kill him off like I did Kaidan in Mass Effect 1, I would do it.
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I'd still say Jacob was worse. Don't get me wrong, every companion's sorry in all 4 ME games are all well fleshed-out and I like them a lot. It's just that Jacob is somewhat more boring (and thus worse) than Liam's incompetence.