Currently I own Lumia 625 Nokia where the OS binds to be optimize, simple and yet high quality product from makers itself. A good thing to appreciate the overall efforts where unlike most mainstream mobile devices didn't care to equalize other category.
Next thing is ASUS Fonepad, where Intel architecture incorporated hence performance wise and as very good battery saver.
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Other inputs based on my experience.
HUAWEI - very poor in terms of Mediapad phones where specifications couldn't handle well on Android OS + hardware problems occur at high risk.
Samsung- one of the well known products, brought mix reviews however some smartphone products fail to optimize correctly when Lollipop is upgraded.
IPhone- no need to surprise, Apple products are well reliable in mere fact they focus on same architecture with little revisions.