I am not brand loyal, I don't think me or anyone else here has used enough phones for a good amount of time to really form a good judgement. Of course most of you are going to say Samsung, because they hold a huge ass market share.
But I am currently using a Samsung Galaxy Reverb (Poor mans version of the Galaxy), I have used ZTE (Android), Huawei (Android), HTC (Windows, but not Phone 7), and Kyocera (Dumb flip phone, and bar phone) in the past. Other than the limited features I really enjoyed my old Windows phone the most.