if you guys talking about Epic 5% royalty I think is not a big problem…
if you make $1.000.000, of course the 5% is high amount, but lets talk about team…
example:
Game finish = 1 Year /12 month
Team = 10 people
first cases:
with gross profit $3000
UE4= you sold the game and make >= $3K, $3000x5%=$150/quarter
Other engine lets say $30/month = $30x12 month= $360 x 10 people licenses = ($3600)
second cases:
with gross profit $1.000.000
UE4= you sold and make gross profit $1.000.000, $1.000.000x5%=$50.000/quarter (you are lucky enough to make $1.000.000 for every quarter)
Other engine lets say $30/month = $30x12 month= $360 x 10 people licenses = $3600
if you sure you will make that amount of money of course one engine will be cheap and the other will be expensive.
just not only thinking about the royalty or prices, thinking about your lovely studios too, how long you will finish your game, how much people, will your finished your game or not, and from the engine itself, Epic give you 100% source code, if other competitive engine give their source code by “special price” we dont know how much the price isnt?
But if you sure you will make a big gross profit and 5% is to high, dont forget Epic offer special custom license… 
But, stingray is new, people love a new thing, and I love it too.
The downside that I dont like in stingray is they not C++ (CMIIW) , Im not experienced programmer so I dont have much time to learn a new language or new visual scripting system, I think its better to use my precious time for improving my skill with my current engine, UE4