It depends on what to you're looking for and how many days you have for the trip. if you can, you should try to visit all three. Baku and the fire temple nearby (Ateshgah) are worth a visit but it is a small place so 3–4 days will be enough. read more
Briefly say, Baku is a modern world city with Eastern in-between tints. Tbilisi - I love this city! No matter how it is different from Baku, and from my culture, Tbilisi feels like my second home. This is a city located in a very heart of Caucasus mountains, thats holds the spirit of Caucasus that is missing in Baku. read more