Do you have a specific budget or features you're looking for? I'll list some things that define the biggest differences between the most popular Android phone brands.
Samsung - full of features, in your face.
HTC - Snappy, beautiful setup, clean looking.
LG - Similar to Samsung I would say.
Motorola or Google Nexus - Stock Android, not as much features but very clean, slick, and powerful.
If you're on a budget and looking for a good android phone that will never let you down, I'd definitely go with something from Motorola. If you're not on a budget and looking for something with the most features to show off, go with Samsung, or LG.
If you want a phone that feels very premium with a nice looking screen setup, then I'd go with HTC.
All are great in they're own way, but you have to find the one that's right for you and everyone has their own preferences. I would read some reviews before making a final decision. Hope this helps!
Posted via Samsung Galaxy S5