I've decided to go with a simplex noise instead of Perlin noise. This is the noise implementation I've ported from Java to C#: SimplexNoise
Smooth Unity Perlin noise
Jagged Simplex noise
How can I make the simplex noise look more "smooth", just like Unity's Perlin noise? Blur is one solution, but is there an easier way to tweak some parameter of simplex noise? I want my simplex noise to look similar to Perlin noise.
Your simplex noise looks wrong: I suspect you haven't normalised it into the (0,1) range, so some of the noise is getting truncated to zero.
They should look pretty similar, see the images on this page: