I am nearing the end of my Ph.D. I need to publish a bit more, but am unsure what to do. So far I have published two rather large articles with my supervisor, where we develop new methods. I have also published a smaller article along with an external collaborator, where some of the new methods are used. My supervisor thinks we should publish another large article together, while I lean more towards two small ones alone. I am not guaranteed a post doc anywhere yet, and will most likely have to write my own grant application. What would be the best thinking in terms of securing external funding afterwards?
A direct answer for your question would be that quality would be better than quantity in this case.
By a larger paper would not always be of a better quality than a smaller one. But if you mean a paper with more extensive research and collation of results obtained from rigorous time consuming experimentation, then yes. Such a paper would carry more positive impact than multiple smaller ones that you could use just for the count. This is from the viewpoint of your advisor.
Some may prefer increasing the number of publications, but it would only matter if they are published in reputable journals, in other words, if they all hold quality (at least in most cases).
So if you intend to sacrifice quality for quantity, my honest opinion would be the same as your advisor's.