I have played Tropico 1 and 3-6, and I think this is by far the best in the series! It has the best of Tropico 4 (including the re-introduction of election speeches, which was a feature that was absent from Tropico 5 for some reason) and 5 (like the Tropican constitution, research, and era progression). It also has a bunch of other features that were never done in the series before, such as advanced transportation services, being able to play in an archipelago instead of one big island, and The Broker, which is the person to turn to if you want to spend your Swiss bank account money as well as giving you tasks to add on to your Swiss bank account. Also, the graphics and music were great. Of course, I have to admit that it is a bit difficult than the previous games, which is off-putting for casual gamers, but if you play your cards right, then you will have a good time. Other than that, I find Tropico 6 to be a refreshing entry in the series. (Note: I originally bought this game on Steam when it first came out, but then re-purchased it and "The Llama of Wall Street" DLC here, because I already own Tropico 1-5, which I purchased from here).
I've bought and played this game on Steam when it was on Early Access, and it's actually a fun and addictive game! The game is like Stardew Valley, but set in a 3D world, and instead of a farmer (although this game has the ability to raise animals and grow crops), you play the role of a builder. Sure, it's not perfect, as there are some things that needs improvement (including the voice acting, as not every line that the citizens of Portia says has voice acting, among a few other things), but the final game had just launched three days ago. If you love games like Harvest Moon and Stardew Valley, you'll love My Time at Portia!