In my limited experience:

3mm PLA: By the time I get to the end of a spool w/ PLA, the filament has become somewhat hardened and brittle, causing problems towards the end of the spool. This is function of filament "freshness" and the shaping forces imposed by the spool.

3mm ABS: While there does seem to be some additional curvature imposed towards the end of a spool, I'm encountering no embrittlement or "freshness" problem, thus, I don't really have any spool related problems w/ ABS.

I have no experience w/ 1.75mm, but I can imagine that the 3mm vs 1.75mm issue is affected by the properties of the material.