Requesting comments from someone who has played both.

I loved DK2 and am looking for another game in the genre.

I played both and they're both great.

If you're looking for a bit of a breather from the whole fantasy genre you get with the Dungeon Keeper series, I'd say Startopia's sci-fi setting is definitely going to make it. If, on the other hand, you're just asking about a superior Dungeon Keeper 2, then I would recommend sticking to Dungeon Keeper.

They're different beasts, Dungeon Keeper and Startopia, I can't quite suggest one over the other, because they're different games. Startopia has more "traditional" sim/managerial aspects, whereas Dungeon Keeper seamlessly blends those elements with action and strategy, becoming its own game. I have both titles in the highest regard, for different reasons, so, like I said, depending on what you are looking for, either one could suit you.

First of all: both are absolutely excellent games. Startopia has more of a sim/management feel than dungeon keeper and a much slower pace. For example, most of the mission objectives in Startopia are economy related, whilst most of the objectives in Dungeon Keeper are combat/conquest related. In Startopia you are more concerned with keeping your visitors happy and content while simultaneously figuring how to stockpile enough resources to sell though trade.

The essential similarities between the two are that in both you expand by building rooms that serve very specific purposes related to your base as a whole. Each(most) rooms attract certain creatures to your base that stay there as long as their needs are taken care of, that can differ from creature to creature. Some creatures types don't get along very well. There can be multiple factions on each map, which you may or may not decide to eliminate through combat using your creatures.

Startopia expands on the economy and base maintenance aspects (eg trash accumulates and rats breed that have to be taken care of lest you upset your denizens) For each room that you build you can place objects inside the room where you always aim for a efficient layout. Also not everything is a room, eg there are buildings like a hotel that you can place that earns you money from aliens staying there. There is a 'nature' deck (which is pretty damn awesome) where you can create different climate zones (arid/tundra/wet etc) on which you can grow various plants which can be harvested and traded. The combat works more or less in the same way, except it is far more cumbersome from what I recall. Also, where in DK you have imps, in Startopia you have little yellow robots (that can also be 'leveled' or more specifically, upgraded)

Dungeon Keeper 1 is so much better than DK2, I would give DK1 a try if I were you

second! :)