i5 4440 vs i5 4590 vs i5 4690

The 3 are almost the same,the only difference is the clock speed (the 4690 is clocked at 3.5 GHz,4590 is clocked at 3.3 GHz clock speed and the 4440 is clocked at 3.1 GHz)
If you're on a tight budget,get the 4440.If you can afford the 4590,then get that one. :)

 
Not much.Maybe only around 11% difference between the 4440 and the 4590 and 9% difference between the 4590 and the 4690.
What this tells you is when using an i5 4590,you won't see much of a performance increase against the 4690.Same with the 4440.You won't see much of a performance increase when using a 4440 against a 4590.
My recommendation is to get the 4590. If the price difference is too big between the 4440 and the 4590,then get the 4440.If not,then it's on you to choose.Once again,you don't need the 4690.