there is not really a "best android phone" out at the moment. and there probably never will be one.
- high-end normal size: galaxy s5, htc m8, lg g3, sony z3 and the new moto x are all great phones. all have advantages and disadvantages, depending on your priorities (look, features, camera, haptic feel, water/splash proof, speaker/sound quality etc). also, availability of some phones is limited to some carriers (in the us).
- budget phones: nexus 5, oneplus one are both great phones and substantially cheaper than the listed phones above. the old moto x (2013 edition) is also a good choice for many people).
- budget budget phones: moto g and moto e are both really solid phones if you want to spend even less (sub200$ full retail price). for many people, this should be more than enough. also, motorola will have a very fast update to android L. afaik there are no real reviews out there yet for the new generation of the moto g, but it should be similar, but bigger than the old one). if you know what you're doing, there are many chinese knockoffs (or just chinese phones) etc available for great prices, but if you don't know a lot, i'd suggest to just ignore this option).
- phablets: afaik, the note 4 is by far the best candidate here. if you want a phablet and not really looking for anything special, just buy the note 4
- high end smaller sized phone: just want to mention the sony z3 compact. sony is (nearly) the only company that really makes high-end smaller sized phone (4.6" screen). the s5 mini and the m8 mini are more or less average phones that just steal some of the design features and the name of their big brother, but the z3 compact has all the great features included. availability is / will be quite limited in the US afaik, but anyway, for everyone that doesn't like 5"+ phones, have a look at the z3 compact.
- if you want a stock android experience, the nexus 5 is as close as possible (aka completely stock). all the motorola phones are very very close to stock, with some useful and nifty additions. furthermore, chances are very high that the next nexus phone will be presented at the end of october, but nothing really substantial on this front yet.
that should cover some of the most often asked questions.