This is funny to me because I use all three for different purposes.
I will
never feel comfortable logging in to any secured account on a Windows machine, and I take precautions and stay up to date with threat vectors on my Linux and OS X devices also.
The Windows machines I use accumulate junk at an unreal rate, and Windows Defender is absolutely useless in detecting the more dangerous threats.
If you'd like to prove me wrong, download a
Hitman Pro trial, and see how much spy or malware it can find on your system in a single pass.
In any case, if you're a well capitalised trader, two factor authentication is an absolute must.
Please enable it ASAP, sure it's a bore but it's worth saving your capital.