Sloth and Torpor is the #1 for me... a perfect case in point being the meditation session I had a couple of hours ago. Ten minutes in and I switched postures to be lying down. About a minute later I was asleep.
It's not laziness though, just tiredness.
"Having understood name-and-form, which is a product of prolificity,
And which is the root of all malady within and without,
He is released from bondage to the root of all maladies,
That Such-like-one is truly known as 'the one who has understood'." (Snp 3.6)
"Whether I were to preach in brief, Sāriputta, or whether I were to preach in detail, Sāriputta, or whether I were to preach both in brief or in detail, Sāriputta, rare are those who understand." (A I 333, Sāriputtasutta)