Upgrade from Asus Transformer TF300T

I really loved this tablet and am looking for an upgrade to as it is just a bit too old now.

What i really liked about it was the detachable keyboard dock which has a second battery plus a full size usb port, plus a decent mouse pad, plus a full size sd card slot and typing wasn't half bad on it either. All that on top of the tablet itself having mini hdmi out and micro sd card slot.

Is there anything out there available with these features for about the same money as i paid for the TransformerPad originally ~€500.

I know there are plenty of bluetooth keyboards but obviously without any of the extra features listed above.

Asus seem to have abandoned the Android Transformer Pad line a few years ago with the TF701 so do any other brands provide what i'm looking for. It doesn't have to be Android but i'd worry that for my price point a Windows machine would be brutally underpowered.