Depends on who did the ultrasounds, but actually, I would tend to go with 12 week ultrasound as the more accurate predictor of those you mention.
LMP method assumes you have an "average" length luteal phase, whereas in fact this varies by +/- 2 days amongst individuals.
In early ultrasounds where the fetus is still quite small the variations in size amongst individuals are also not great, so it's actually a very good indicator. An earlier 7 week ultrasound would be generally an even better predictor.
Ultrasounds later in pregnancy show more variation in length and sizing of the baby in utero due to usual difference amongst the population, so you wouldn't tend to change your estimate of due date on those.