I will try to elaborate further, by most powerful I meant which has the highest capability, which is most advanced but what is most important are physics and which would you consider best when producing a fully polished iOS / Android game.
Unfortunately, that doesn't help clarify. "Most advanced" and "highest capability" is exactly the same sort of impressive-sounding but meaninglessly generic terms as "powerful" / "best" / "awesomest" / "greatest" / "coolest" / "polished" / "flexible".
By saying you need "physics" and "2D", those are good requirements. They are concrete ideas. iOS and Android are concrete targets.
Saying "most advanced" or "highest capability" doesn't describe anything. Those are marketing terms.
Those are typically what people say when they haven't thought through what they actually need.
What does your game require?
- 2D graphics
- Physics
- iOS support
- Android support
- ?????
- ?????
- ?????
Using your actual concrete requirements, you can then look at different engines' feature sets and see if any meet or come close to your requirements.
I'm making a 2D RPG. Here's some of my game's desired features:
- 2D graphics
- Multiple layers of tile-based, freely-placed / freely-scaled, and scrolling art
- Particle effects for combat skills
- Basic collision
- Circle (the player) to axis-aligned squares (the world) collision.
- Sound
- Walking sounds depending on the terrain the avatar is walking on
- Interface sounds for clicking buttons and such
- Combat sounds
- Environmental sounds (birds, flowing water, etc...)
- Background music
- Logic
- Scripting support for in-game events (i.e. sequences of actions played out onscreen to form a "scene", such as a messenger running up to the player to talk to him).
- NPC dialog
- Multiple-choice responses for the player
- Villagers walking around towns in pre-set paths
- ...and more besides
No engine supports all of what I need automatically for me (though some come close). Some engines are so overly general that I could build what I want on top of them, but that doesn't save me much work. So I'm writing my game from scratch using existing 3rd party libraries. This is how most 2D games are made.
2D games vary more than 3D games do, so engines make more sense for 3D than they do for 2D, because most 3D games share more in common with each other than 2D games share in common with other 2D games.
Some 2D engines are genre-specific, like RPG Maker and so on, and those are helpful but when they are too narrowly-focused (like RPG Maker), it also is limiting. So it's important to figure out your needs in advance, and decide if a particular engine helps you more than it limits you, for the specific game you are making.
By figuring out your needs, it also helps you figure out what you don't need, so you don't get lured by an engine with a laundry-list of features that don't actually help you.