Buy any of them, they're all beautiful, especially if you don't have a lathe at all.
But there are pros and cons. For myself I can only sensibly offer an opinion for the Myford and the Bantam, as these are the machines with which I am familiar. Even that isn't entirely accurate as the Myford is a ML7 not a Super Seven.
I have two friends with Boxfords, they love them. I bought a Mark 2 Bantam to replace my aged Myford S7 because that was what I found on the market at the time. Needless to say I still haven't quite got round to selling the Myford – it still serves a turn and although I'm always struggling for space I'm still attached to the S7 and can't quite bring myself to dispose of it.
The Bantam in the links above is an early Mk2 so it has 5.5 inch centre height, not the 6.5 inch centre height of the later ones and of the Student. It looks a bit green in the pictures, but that's the lighting. The advert says its a good specimen – only one way of testing if they are telling the truth, go and see it. If it's not been bashed about it will be a nice machine, easier to use and more robust than a Myford, but accessories are like hen's teeth. Trying to find fixed and travelling steadies – certainly at any sensible prices – well you'd be better off starting a unicorn breeding centre. If you want to do milling in the lathe this isn't the place to start. Beware of buying changewheels for it, they seem to come 16 and 14 DP and I've never found out why – obviously you can't mix and match.
But the real reason for posting this is to introduce my experience with using the Bantam on a single phase supply. Initially I simply swapped the original motor for an approximately equivalent single phase capacitor start motor, but I was very disappointed by the crash start this imposed on the gear train, and converted it back to three phase with a VFD. This gives the advantages of speed control but also soft start which just works quietly and is docile and a pleasure to use.
In the process, I have forfeited the higher range of speeds. The basic Bantam is a 800 RPM top speed machine (the later one goes to 1000) with the motor running at nominally 1400 rpm, and the higher speeds are driven by running the motor at 2800 rpm. The original motor on mine was a two speed motor, with two separate sets of windings and the control gear included a multipole switch by which the motor speed was controlled. All very well, but this motor did not have a star point brought out the terminal array, so I ditched it because I couldn't connect it in delta to be compatible with 230 volts three phase derived from a single to three phase converter (VFD). Knowing a bit more about it I now know you can often "find" the star point and re-configure the motor for delta, but it's too late as the motor got lost in the last factory move.
So I get the higher range of speeds by over-speeding the motor – I.e. running it at 100 Hz, at which it struggles. But for almost all of what I want to do the four pole 1450 rpm motor run at 50 Hz is the bees knees, and it's not worth the cost and aggro of experimenting further with it.
Conclusion – running a three phase motor on a single to three converter is easily said, but think it through first.
Hope this helps, I do go on bit so I'll stop for now, if you want to know more post a reply and I'll develop this further.