On well supported phones, how successful devs been on beating KNOX?

Also ex-GS3 User looking to upgrade...what company of phones should I look into that have the battery life, ease of rootability/custom ROM support, and physical form factor?

Unbelievably dissapointed in all this KNOX ****t I have to deal with ant hte fact a brand new GS5 I got isn't able to be rooted and probably wont be ever.
I also love the removable memory/battery of the GS3. Any other phones match this criteria? HTC/Asus Zenfone?