why dont CM and AOKP and PA use the GPE as their base?
They only use open-source drivers and code. The GPE edition has some closed source stuff and is still Sense based, which is not compatible with AOSP.
I'm thinking of upgrading my iphone 4 to the HTC one, i've never had an android phone so is there a huge difference? I really like the look of the HTC and from what i can gather the specs are really good, how much of an improvement would it be over my iphone? I currently have two phones im interested in getting, either the sony experia Z or the HTC one, im swaying more towards the HTC at the moment.
Another plus im seeing with getting the HTC is the memory, right now my iphone only has 8GB and that is nothing where as the HTC has 32GB.
It's a huge difference. It may take some time getting use to Android, it depends on your personal preferences if you like the way Sense 5 (HTC's version of Android) works. I know there are some which found it too confusing and switched back to iOS, and others who love the more customizable options.
The Xperia Z is a nice phone as well but personally when I saw it in the shop, it looked like a slab of boring plastic... And the screen on it has poor viewing angles as well.