I have owned both cars.
Toyota engine vs a Porsche engine- powerwise similar but Porsche delivery /sound were far superior
GT4 has a mostly GT3 derived suspension which I felt was superior marginally
Steering- Porsche was superior
Interior/comfort- very similar
End result - i sold the evora after 600 miles and have a 718 gt4 on order
I will pick GT4 for sure (I have 981 GT4):
Say, changing the clutch >If it were me I would get the Evora because I like strange/rare cars! (owned a Saab 9-3, Volvo S60 R-Design, Exige, etc..).
I also wonder how the Evora compares to the GT4 in expendables/maintenance which really add up when tracking a car. I imagine the Evora ownership should be cheaper in general because it has a Toyota engine...