Easy IDE, libraries and examples?
It is highly subjective if an IDE is easy or not; and what's easy to me isn't necessarily easy to you, and vice versa. Both keil and IAR are very easy to use in my view for example.
As to libraries: 1) you can always roll your own; and 2) the ST library is very flexible and fairly proven at this point;
Examples? There are tons of them.
Yes, the STM32F4 boards are tough to beat in terms of performance / price.