Pirates have a better starter going today but the downside is that the Cubs bats seem to have come alive in the last week. They actually won two series on the road (SD, ARI).
Pirates bats aren' doing too bad either (split the series with CIN, and won series with LAD 2-1) but they are not scoring nearly as many runs as the Cubs are lately. The concern I'd have is Cubs have a little momentum going and they have better bullpen.
Too many questions to pick either team.
Good luck.