For algorithmic trading, once you actually have the "brains" of the methodology - meaning the design of the systematic decision making process for your algorithm - I think you would find the question of which language to use to be a trivial one - for you will have needs and demands placed by your algorithm, and there will be a language best suited for your use.
Actually writing the code is the easy part once you have a profitable mechanical strategy. The question becomes - which environment is best for developing such mechanical strategies? Well.. again, depends on your needs
I personally use R/Python/C -> R for data analysis, Python for Data wrangling and other small data manipulation for which writing C code would be too cumbersome, and C for when I need to work with very large amounts of data - because sometimes waiting times for R/Python code to do something can be 100x slower than C -> So when I might need to wait a month+ for some code to finish running, I code it in C.
For you, I suggest R+MQL. Much of data analysis is so very pleasant and easy to do in R. When you suspect a certain method might prove profitable, you can quickly and crudely code it in MQL and check if it is viable.