I've been using Swift/Objective-C to make my last two 2D games for the iPhone. I first worked with storyboards and then SpriteKit, which I enjoyed. I want to further my experience in programming and creating games. Where should I take my next step? Into Unity?
I would strongly recommend unity because it is cross platform, properly supported and not going anywhere.
What is the best ice cream? Chocolate or Vanilla? All engine's have their positives and negatives. it mostly comes down to preference though. For example, I am a C++ guy so any engine I pick would need for me to work in C++. So I would probably use Unreal. That is me though. From what you have said, I would also recommend Unity. it's cross platform and easy to get things running.
It depends a lot on what you want to make. Unity has a lot of features, but also has a very large footprint. Flappy Bird will be about more than 10MB if made with Unity
The footprint is only 12-16MB. It's nothing compared to development time saved by Unity and Asset Store.
In comparison, the original Flappy Bird is about 2-3 MB. IMO, file size is something actually important for many, especially casual gamers (with 8-16GB devices, or are downloading games on 3G)
I agree with this. For a game as simple as Flappy Bird it would be vital to keep the file size as low as possible. Unity is overkill as an engine choice.
I can't see any reason to drop the power of Unity and all its plugins (+ our own tools) for a small game. And most of the modern mobile games are over 30-50MB anyway.
Considering you used Swift before, I would recommend using Corona SDK if you're still aiming for 2D games. I think you could make well use of Lua with Corona SDK.