About 9 months ago I was in the same situation that you. I needed new Android phone for amateur apps/games development. However it was not obligatory for me to have Android 5.0.
After long research I have chosen Motorola Moto G (2nd gen) and I am very happy with it. It had very good price/performance ratio at that time. I also bought it even cheaper than in the shop at online auction (it was not new but almost new and not used).
Good sides:
- Very good price/performance ratio
- It is cheap but brand phone. Motorola sign should at least in theory guarantee basic quality. In my case it does.
- Phone is solid, it case and buttons look and behave like in brand phone, not like in chinese fake.
- It has pure android without any overlay (opposite to for ex. samsung phones which have producer overlay). Because of that phone is faster and don't have many unnecessary "fireworks"
- Nice screen. Good colours, big size, very good angle of sight. At the beggining it was too big for me but I got used to it. Now it is perfect for me.
- Battery in scale from 1 to 6 is 4+. In my opinion for Android phone it is quite good.
- There might be an update to Android 6 but I'm not sure. You have to check it on your own.
Bad sides:
- My model doesn't have 4G support (it has 3G only), but there are models with 4G support (for higher price, so I have chosen cheaper one).
- Battery is build in, so you can't change it easily when it looses capacity after some time. However I heard that it may be changed by using special tools (in service or you can do it on your own)
- There are no "fireworks", you pay for what you see. For me it's fine, but there are people who like when producer give them some amazing software or something like that (Samsung puts those "fireworks" in it's phones especially in galaxy series).
- One small downside: you have to install additional usb drivers so Android Studio, Eclipse or another software using Android SDK can recognize phone. In fact 90% of phones needs that.
- Probably you can find some noname chinese phones which have even better parameters for lower price. Althought, when there is no make they quality may be bad.
- Now you can maybe find some brand phones which are cheaper or offer better parameters for the same price. I don't know how current phones market situation looks like. I can only tell that 9 months ago moto g 2nd gen. was a good choice, nothing more.