Having played, and loved, them all for years and years I'm curious to hear your opinions on which one was the best.

Creatures 2 is my personal favorite, I like the art style a lot. But in case of the Creature's series it's more of an evolution so basically all next games in the series are better than the last. More complicated genome, bigger world, better stuff to mess around with.

Wasn't Creatures 2 much bigger than Creatures 3? It's been a while since I played C3, but it never felt this big. Maybe it was just a placebo thing with the whole instanced world vs. parralax world.

C2 always felt more packed full of stuff, and it had more "game"-y elements. Like unlocking the different kits, exploring with the norns, etc.

C3 was either the same size or bigger. The thing is that the core mechanics were the same, you also had to explore and discover things with your Norns to find and power all the systems of the ship.
The same elements were there, but it felt a bit different as the developers tried to make you feel that you're not in charge of a program with windows and you unlock apps, but that you're playing around with a real living ship. Eg. the medical kit actually requires you to put a Norn into a medical vat in a proper section of the ship and only then you can inject them all kinds of chemicals and ultimately kill them with cyanide. In C2 all you needed is a popup window.
Also the Norns are easier to control in C3 and are a bit smarter ;) Same with other races, Ettins got more annoying, damn kleptomaniacs.
Although you have to be aware of a bug in C2 where the Norns just got dumb as rocks within an hour of their lives. There are Norn Breeds still available online that fix this genetic disorder. I'm not sure whether this bug is fixed in Albian Years or not...

Ah yes, the infamous OHSS (One Hour Stupidity Syndrome) I can happily say I've never been effected by it.

Maybe you know. I postes this some time ago:
http://www.gog.com/forum/creatures_series/c2_color_change_and_a_weird_question/post1

I played all three parts and while I have a feeling of happy nostalgia towards Creatures 1 and 2 I prefer to play Creatures 3. :)

Creatures 2 is my favourite. I just love the world, it's very diverse and feels alive. I do have some issues with it, One Hour Stupidity Syndrome being the worst offender (Thankfully, there are mods). It is also VERY buggy, and the spot where Grendel eggs hatch makes no sense.

But I think C2 has aged more gracefully than the other two. Graphically, it still looks awesome. Creatures 1 looks good too, but it only has 256 colours and it really shows on a modern monitor. As for Creatures 3, I was never a fan of the Norns' new look... I haven't played it much, but I didn't like the gadgets either. I should probably get Exodus eventually, maybe I just haven't spent enough time with it. X)

Creatures 1 is my favorite, I think this is because I grew up with this game. Every time I launch the game, I remember those passt summer when I spent my days whith an old friend trying to make my norns reproduce...

Then I moved directly to C3, I never felt accustomed to Creatures 2 because of the Norns' appareance and the overall graphics (I don't like these "bad precalculated scanline 3D graphics" in comparison with the physical set of Creatures 1).
My second favorite game is Creatures 3/Docking Station, but I still think that Norns in C3 are too intelligent ; they can take care of themeselves where in Creatures 1 even an adult Norn can die because he forget to eat. In C1 you have to take really care of your Norns, where in C3 you can let'em live their live alone. Moreover, the C3 Norns have a quite short life time, where in C1 I had 26 hours old norns sometimes...

Thanks. I thought Creatures serie was a dumb game, for I only played C1 and didn't understand why so-adult Norns can't live by themselves. I'll play C3.

so my norns keep turning into frogs? what do? They are also multifpying.