What are your thoughts? Where one is better then other one?
I think it's more a question of preference.
Apollo is perhaps more of "traditional" solution for a entity/component framework, where you have logic with your components. Some may be more convenient with this, and most will probably get started quicker with Apollo because it builds on existing preconceptions about programming.
Artemis on the other hand is more "untraditional" because it's not as object-oriented like Apollo and is aspects/systems oriented, and is perhaps more experimental and thus not as proven in design although it's pretty well optimized and decently smart. Artemis is something like a introductory framework to this world of dealing with components as pure data and systems as aspects that process or deal with that data. People may have trouble of knowing exactly how to write their games with Artemis because it requires different thinking.
I don't really think comparing the two is fair, they are naturally different. I think Artemis is more abstract because it doesn't provide you with things like rendering, like Apollo. I'm pretty proud of Artemis, because I put a lot of brain into it, and I don't intend for Apollo to be some sort of replacement, because it's a totally different ideology, and I will also be developing Artemis further.