Wikidata. Statements are added all the time to specific items and that reflects well on the quality of those items but the underlying health of Wikidata is probably best expressed in its statistics.
The latest statistics show that we can finally say that "50% of our items have none, one or only two statements". Arguably not much can be said about these items and consequently these items are not informative. The trend however is wonderful; it shows in the graph; slowly but surely Wikidata is gaining data and by inference becomes more informative and useful.
The next challenge for us will be to be able to say "50% of our items have none, one, two or only three statements".. That will be a happy day.