I haven't had the chance to really test out Unreal 4, altough I would love to.
But I have some years of expierience in Unity and can tell you, as long as you don't want to do extreme stuff (1), Unity is fine out of the box. More and more pro studios are starting to use the engine, and there might even be some AAA class projects done with it (I wouldn't know any though)... Heartstone will use it, for example.
As far as I can tell, Unity does not have "less tools" in it. As I said, I have no knowledge of Unreal 4, but the Unity editor is among the best you can find in any engine. Trust me, I ditched a Graphically more evolved engine (that was plagued by other problems also though) for Unity 4 after having ditched Unity 3.5 for this engine 2 years earlier, just because I really got fed up of the very basic and crude editor of this engine. It was a chore to get anything done.
The Unity editor is a dream to use in comparison.
The catch with unity is that some of the more advanced features are hidden behind a paywall as you need either the pro version (1500$), or 3rd party tools from the asset store (most of them are also paid versions).
Thus, make sure that either you don't need these features, or you have the budget for the pro version and the 3rd party tools you need. If you need the features but lack the budget, Unreal 4 can be the better option (even though AFAIK it lacks the community support of Unity, especially the paid tools from the asset store which can really be extremly professional tools for sometimes incredibly low prices).
As said, you also need to be aware of the limitations of Unity. It is certainly not the best performing engine, altough this is difficult to compare. I would give Unreal 4 the benefit of the doubt and call it the better performing engine as Unity 4, to my knowledge, still uses the very old engine core of Unity 3, still has no 64bit support (if you REALLY need it), and has some "hacked" solutions for some of its newer features (using deffered lighting only instead of a complete deferred renderer e.g.).
The engine has been built as general purpose 3D game engine, so some features like seamless terrain loading are not built-in as in other engines (no idea about Unreal 4), some more advanced features of the Unreal 4 engine are missing until now like the mega textures (no idea though how useful that is).
That said, be aware that Unity 5 is coming out soon, and it looks like there will be a lot of changes coming with it. Native PBR, a new powerful cutting edge lighting engine free of charge that is not included with Unreal 4 yet, a new GUI and Audio system and more.
If you compare Unity to Unreal 4, make sure you take that into account. Seems like Unreals new low price of entry has really forced Unity to speed up its pace. One can only hope that either prices will also have to come down in the future or more features will transfer from the paid to the free version.
In the end, you really need to come up with a list of mandatory features, a budget you are willing to pay, and think what you will really do with the engine in the foreseeable future. Don't be fooled by the big Name of the Unreal Engine. Unity has come a long way since its indie root days and is starting to compete with the big boys.
Also be aware, if you want to go commercial, the Unreal 4 royalities, low as they are, might still cost you more until you are able to pay the full license price of Unreal (some 100k$) than a pro license for unity and some assets from the store.
EDIT: Oh, forgot you mentioned Android and iOS. You need special licences for that in Unity. As long as you are not using the pro version, these are free of charge also nowadays AFAIK (which is a wise move by Unity, as all others include most platforms with their licenses).
If you need the pro features, you have to get a SEPARATE license per platform (only Windows/Linux/Mac is included in the base licence), driving your licence cost up to 4500$ per seat... pretty mad, if you ask me. But of course, I am not interested in Mobile dev, so my opinion on that topic does not really count :)
And always be aware that there are limits about what an engine can do, no matter how powerful it might seem (see below). Really pick your battles...
(1) What I mean with extreme Stuff:
When I started out with unity, I was a wee scrub when it came to game development (was already an expierienced programmer in other fields though), so I made a lot of mistakes and really wanted to achieve too much.
I tried building an 8x8 KM Terrain with 1x1m Heightfields for example. A pretty stupid idea in hindsight, but it quickly showed 2 limitations of Unity:
a) terrain resolution is limited to 2048x2048 pixel Heightfields. If you need a bigger Terrain with this high resolution, you have to use multiple terrains, which in turn will give you trouble with stitching them together, or the terrain LOD (you can switch that off, though it will degrade performance)
b) no 64bit support for the editor. Having more than n high resolution Terrains in the scene (n being somewhere between 6-8) will crash the editor. Or at least it did in Unity 3.5
Then I found out how good the deferred path looked with a nightscene and multiple lights. So I went overboard and found out that Unity doesn't seem to prune lights that are not visible (for obvious reasons though) and that the way Unity does realtime shadows is driving up your polycount and draw calls like mad. And also, because Unity to this day has deferred lighting instead of a full deferred renderer, a lot of the objects have to be rendered twice.
But of course:
How many games REALLY use extremly large terrain, without any tricks (spatial partioning with portals and so on)? Is there even a game with such a high terrain resolution (it looks nice, but you are better off with Polymodels for the areas you really need the resolution in)? What game today uses nighttime scene with a crazy amount of real time lighting?
If the AAA guys had troubles doing it, you as an Indie will certainly not be able to do it with todays engines, no matter which.
