I'm getting ready to do my first extract and I just read in the DMT handbook that vinegar isn't very effective for an a/b extraction.

I see that almost all teks say you can use it though.

I also read that citric acid can end up in the final product.

These are the two acids I have immediate access to so I'm trying to get input into which one I should use for ml better yields.

Have used vinegar for most of my extractions of Phalaris and Acacia with good results.
Juice from lemons has always gotten more alkaloids though.
Guess it's just easier getting a $2 jug of vinegar than a ton of lemons so you don't have to go out to the market everytime, but it is preferable to use more natural ingredients.

Have never used straight citric acid though.

Both fine

Both have worked well in my experience, but neither seemed to work better than the other.

I don't see any way that citric acid could end up in the final product, unless one were using it to backsalt alkaloids out of a nonpolar solvent.