Python's ecosystem is great - but Julia's is growing incredibly fast, and in some cases Julia has already surpassed what is available in other languages (for example, take a look at the whole differential equations ecosystem: https://github.com/JuliaDiffEq). Also, Python's ecosystem is only a 'pyimport(name)' away (using the PyCall.jl package). Same thing is true for R and a number of other languages (RCall.jl, JavaCall.jl, etc.) I've been using SymPy, QisKit, matplotlib and other Python packages with no problem in Julia.