IPhone 4s 16 vs Moto G 16Gb?

So i'm having a Iphone 4s 16 gb and actually i'm confused as i want a moto g in its place. I want to ask should i go for this option as ios 8 is about to come. I an doing all this stuff because of that i'm not able to send music over whatsapp nor recordings and small-small things. Please tell me what to do?

New iOS will probably have some great features, but will probably slow your phone down a tad. Normally happens with new iOS and phones that are 3 generations old. Example, iOS7 on my sisters iPhone4, slow, very slow.

The iOS option is good but I'd recommend a Moto G because the 4S is really old and it wil EXTREMELY slow down your iPhone when updated, even iOS 7 might lag, so go for the Moto G, a really good phone, nearly stock Android, cheap, compact, bad camera and powerful too.

Or get an iPhone 5S when the price drops after the release of iPhone 6.