I use an iPad mini (1st get) to drive a Qu-SB. Fast, responsive and unobtrusive. Screen is generally large enough – the only issue I have is my finger sometimes misses fader knobs which are quite small – I have to be precise.
In terms of the wireless access point (separate topic I know but others have commented), I find the Apple Airport Express (2nd gen) very reliable – never missed a beat. My Qu-SB is in a shallow 4U rack case and the Airport is velcro’d to the inside rear of the case, permanently connected by LAN cable to the mixer. Wifi signal is fine for 10m distance but I take it out if the signal dips.