I believe that none of them have any iPod touch alternatives. I remember Samsung tried years ago but the device flopped and failed. If you want a device to play around with Android or Windows Phone, there are some decent low cost options available for both platforms now. Moto G, Lumia 520 / 521, Lumia 635, etc.
I have thought about the possibility of getting those cheap "contract" phones to be used solely as a media player. Fry's usually has one for $40. The specs are not great, but it has an SD slot so you could add 64GB or something. Put it in airplane mode and the battery will probably last a good while.
But for me, the biggest problem, it the lack of something like iTunes. A centralized program. iTunes is really what makes me stay in the Apple ecosystem. I think it's great.