The first four are available on GOG, DRM-free.

IMO Anno 1404 (+ Venice) is the best version. Complex but still fun.

1404 gets samey after a while (when going for the monuments). I’d say 1800+DLCs is the same game, but with so many regions and tiers and options.

Anno’s DRM was particularly annoying and had to phone home each time I played. This would have been fine if Ubisoft ran a reliable server, which it didn’t. Once I sat down to play and the game refused to open because it couldn’t phone home.

I then learned my lesson, have not played the game since, and will never buy any Ubisoft product. Too bad, it was a nice game, maybe I would have bought some DLC. But I’m sure the pirates are still getting plenty of DLC. Instead I play Factorio and Paradox games and spend money on their DLC.

Anno has Denuvo. So no rootkit. You are thinking of other games that have Easy Anti Cheat or something like that

I've been burned by Ubisoft before, to this day, I can't replay AC: BrotherHood because even when I launch directly from steam where I bought the game, it has some weird behaviour around linked accounts and the Ubisoft Launcher

Never again, Ubisoft, never again