If you are comparing controllers you need to distinguish between the MSM controllers or the Comware controllers.
I have personally found the MSM controllers to be difficult to manage and to lack a number of enterprise features, for example, HP's firewall solution and IPS / Spectrum Analysis are very very basic (or in some cases non existant) when compared to say the features of an Aruba controller.
The architecture of the MSM access controllers is very difficult to work around as you don't have the flexibility of port confiugration like you do with an Aruba controller. With HP you have an internet and a LAN port and some features can only be deployed on certain ports.
Controller scaling is another issue. Each MSM controller can only have up to 200 AP's and then you need to start looking at teaming. WIth teaming you are limited by what features you can deploy (this is particularly limiting in terms of guest access).
I don't know much about the comware based platform hands on yet, only that it does seem more capable and more "enterprise" than the MSM products.
Support is not very good and neither is the reference documentation. I would choose Aruba every time.
Airwave vs IMC
IMC lacks a lot of real AP / Wireless device support for vendors other than HP. My experience with the IMC WSM and HP's own access points has been poor with a lot of features not working and for one customer, the HP support team actually recommended to stop using it.
IMC doesn't do real time coverage mapping whereas Airwave does as well as real time locaiton of users. IMC only does static predictive coverage plots.
HP is claiming IMC to be a BYOD capable solution but it really doesn't fit together as well as ClearPass. They can do very basic web authentication but this doesn't work with their MSM series and only with Comware wireless. Likewise their switches don't support web auth.
ClearPass can do all the AAA /Guest Access / Device Onboarding on a single box with a much cleaner interface and a very rich set of validated reference designs and this support community which can get you going with almost any implementation. I am yet to see HP deliver a working demo of any of their features that really wowed me.
In summary go Aruba every time!