Unity sucks balls that's my opinion!
If you want to develop indie games there are better options, example "Ogre 3d, Irrlicht, JMonkeyEngine" the problem with engines like Unity and Torque is that they are simply not fundamentally sound. They have hitches and catches and riddled with hidden problems and as soon as you have paid for the product you learn very quickly of how limiting these engines are.
Unity is the worst of the two it has stable programming but provides no source code, the list of bugs that exist in its source tree can end up taking its sweet time before making it into a rolling release or update. Also graphically it is an ugly piece of garbage, if you haven't already played games made with it you will quickly realize what a waste of money it is to spend 1k over the budget for something designed for indie. Thus why many of the free options available are a better solution. With a bit more time and effort on free solutions you can in fact make better content than this engine. No offense to its resounding over zealous community of Mac users.
Torque is a heap of crap its what you get when you have spent years using your own client base like a cash reserve, it eventually ended in a restructuring but in all honesty suffers the same old pitfalls under a new guise. They have turned their engine into a micro managed commodity driven package, each update costing a skyward cost. As an angry owner/protestor of their technology I am beyond outraged of what I dumped my hard earned money into. They are a very tight nit community and rely heavily on the burden of others most probably because they don't know how to make an engine thus why provide the source code. The code itself is bug ridden to the point that somethings sensible or logical don't even exist or simply have you fork over $$ for mods. Now whats even more interesting these so called boiler plate mods to the engine follow their own standard, they come in either personal or commercial license. The cost of those is insane, it is a clearly a dying market an attempt to make profit before pulling the plug on its own customer base.
Where does UDK stand? It stands everywhere and it does so profoundly, you simply can't top its offer. Sure you do end up paying royalties but after a $50k mark which in all considerations is quite a lenient stand point. On the other hand it uses Directx 11 so if your into next gen titles that is where you have to be, if that isn't enough if your into building a resume for yourself UDK is where the stuff happens. Obviously it is an engine that is used by big industry names, with that said it also carries a heavy learning curve but does seem to shine with the fact that they keep releasing new updates. If there is one thing I have come to learn about UDK on a personal level about it, its this, if your going to make serious games for profit with it be realistic and keep your product single player unless you can afford the full cost of the actual engine.