From the perspective of a total novice, it's going to be difficult justifying using "some engine a lot of indie devs use" versus "some engine that all the AAA titles use", even if reality is more complex.
I've actually used and seen other teams use Unity on several released titles on multiple platforms, from 3DS to xbox.
Looking over titles like Hearthstone, Might and Magic X, and Wasteland 2, Unity has a growing list of major titles. It is not just a tool for hobby developers.
The mutual race between the engines is a good thing, I think. The two big differences I see for free users are the sizes of the store and community (where Unity wins), and the availability of source code (where Unreal wins). There are other differences of course, but those are the two biggest from my perspective.
The costs for hobby developers is also interesting from a business strategy viewpoint. Unity is free until you earn $100,000 per year, then $1500 per user. Unreal is 5% after $3000/quarter. Unreal's cost is a diagonal line over revenue, Unity's is a stepped line over developers.
Which one is a cheaper software license deal for you depends on your revenue and your number of developers. For a moderately successful game Unity is generally cheaper. At 3 developers the equality point is $90K (slightly below the limit where Unity requires purchase). At 10 developers the equality point is $300K. If the 3-developer product ends up radically successful, perhaps a million dollars in revenue, that's $50K for Unreal versus $4.5K on Unity.
Overall, I hope both of them are successful. It is an area of abundance and growth, and both tools are valuable to the global communities.