Many card games have power creep, i.e. cards in every expansion being stronger than in the previous expansion. This largely wouldn't make sense for Dominion, but some still wonder if new expansions are stronger than old ones.
I haven't seen anyone do this before, but it's possible. In any case, including Rising Sun in the data is new. I used the data from
Dominion Card Glicko, taking the average Glicko rating of Kingdom cards from each expansion. I figure expansions with 2nd editions feel like recent ones enough to put them in order of most recent release. I've included a plot with the sets in order of original release as well to satisfy curiosity.
2nd Edition release order:
Initial release order:
So it looks like expansions have gotten better over time. I suspect the reason is that dud cards nobody wants are much rarer in new expansions. The strongest expansions are Menagerie, Renaissance, Guilds & Cornucopia, and Rising Sun, in that order. That's a bit tentative since the last two haven't been out for very long, but it's what's in the current data. The weakest are Alchemy, Nocturne, and Dark Ages.
If anyone is wondering, the removed 1st Edition cards have an average Glicko rating of -1.66, much lower than even Alchemy. Promo cards have an average rating of 0.37.