Zeus is by far the best city-builder ever made, nothing even comes close .

Yeah but isn't Tropico 4 just basically a reskinned 3 (that GOG does have) ?

Base game, yes. With Modern Times, not quite. The extra DLC scenarios are also good fun. Sure, you can skip those, but don't discard easily Tropico 4 + Modern Times. And Tropico 5 looks good with all the planned changes ( of course, i'll wait a long time before buying, as i've never been the zero day buy type )

Welcome to GOG!
Caesar 3 is about building cities in the Roman Empire, while Zeus is about building cities in Ancient Greece. Caesar 3 came before Zeus, so if you want you can follow the chronological order of the games and play Caesar 3 first. Zeus has all the elements that Caesar 3 had, but as a newer game is doing many things better. But in the end what matters is your preference. If you are fond of Roman history then choose Caesar. If you like Greek history & mythology, then choose Zeus.
What ever you choose, don't worry. GOG very often has many kinds of sales, and you can find them there cheaply.

wonder what the OP went for in the end... maybe s/he is so engrossed in the game that a week has passed and didn't realise ... awww gaming memories of Red Alert :D

I haven't got any games so far, my local NA bank has been giving me tons of issues since GOG is based in Europe. I have had multiple declined charges(Which were originally seen as fraudulent, which I had to get cleared up) and have had too call my bank on multiple occasions in order to try to get a payment to go through. Hasn't been any fun thus far, although the good news is I found my disk version of Pharaoh and Cleopatra, so I can play that now if I wish to.

Building the God's temples in Zeus is functionally pretty similar to building the monuments in Pharaoh though!
I DO prefer Zeus to Pharaoh though - didn't Pharaoh have this thing where to max out buildings the inhabitants had to have access to more than 1 TYPE of food? Even though the houses just had a general 'food' meter? Or was that Luxuries I'm thinking of? Either way there were niggles...

My advise? Go with Paypal rather than direct bank payment - you can often avoid bank charges that way too...

Caesar 3 has a very different feel compared to Pharaoh/Cleopatra and Zeus/Poseidon. My personal favorite is Pharaoh and Cleopatra although I have returned to Caesar 3 because I missed the Roman setting. However, Caesar 3 does miss out on some of the very nice elements of Pharaoh and Cleopatra. The lack of roadblocks is definitely an inconvenience but not the end of the world. What I miss most though are those massive temples and monuments.
Otherwise the gameplay is very similar (identical even).

Use Paypal . You don't even need to make an account with them .

Well after many days of boredom and frustration, I have finally managed to get the bank on board and the payment finally went through. I got Zeus/Poseidon, Empire Earth, Heroes 3, and Ultima 7. Cant wait to get playing.

Solid choices based on their reviews. If you have compatibility issues, remember to check out the game forums and/or contact Support, and also keep in mind the 30-day moneyback guarantee.

No way you can compare that to building the big pyramid in pharaoh:) And as an experienced Zeus player, I always stock on supplies on previous episode leading that Zeus temple is built very quickly:). And yes you needed 3 types of food in Pharaoh for most luxury houses which actually accommodate much less people leading that your population or prosperity goal can go down due to % of people in good houses goes down:)
But hey some people enjoyed that, for me if Pharaoh had episodes like Zeus it would have been great as its much harder, but the fact that I build a new city from scratch every missions gets annoying after a bit (especially Pharaoh has something like 40+ missions)
Cool hope you enjoy them, now remain marking one of the guys posts as the solution :)

Excellent choices, but you forgot to buy Sacrifice .

Well, OK it might be toned down and easier in Zeus but it's the same mechanic - You lay down the base, build an Artisan's Guild (or Architect's Guild or Whatever) get a load of materials like stone, wood, etc. together and wait!