For me, MCUXpresso is better than STM32 with Cubemx.
In MCUXpresso, you can use wizards to configure Ports, Clock and Peripherals (as you can with Cubemx), and in the SDK there are many examples of source code, practically for everything you want to do. There is nothing you can have in Cubemx, and you miss it in MCUXpresso.
Cubemx does not provide you with a library of examples of source code, and the program it generates is empty, you must write your own software. The functions for each peripheral that you have selected when configuring the Cubemx assistant are there, but there is no example of source code on how to use all those functions.
For me it is essential, you have a large library of examples of source code for all the most used peripherals, so I can see how to make my own program or modify some of the examples by adding new code. For example, Arduino also includes a lot of source code samples, although NXP with MCUXpresso and the SDKs are better organized and documented.
I have worked with PIC32, Atmel SAM S70, NXP Kinetis, Arduino for Teensy, STM32 with Cubemx, and without hesitation I prefer MCUXpresso with the new RT from NXP. From version 10.2, MCUXpresso integrates all the assistants within the IDE itself, so that the ready-to-use program is generated, or by importing any of the numerous sample sources of the SDK.
NXP, it seems that he is dedicating a lot of work to the MCUXpresso, so that it becomes a good working tool for all its microcontrollers, LPC, Kinetis and i.MX, and for now they are getting it.