I'm a professional turner with a big lathe at home, but in my little studio workshop, where the public can wander in to watch me turning, I have a JET, very similar to the one that you've mentioned above. Quite frankly, I'm amazed at just how good it has been. I use it to turn all the smaller items for my shop (key rings, light-pulls, bottle stoppers, pens etc), but I also turn stool legs & tops, candle sticks and small bowls on it. There isn't much to choose between the JET and the Axminster lathe, and both are currently available, so I'd say that as long as these offer you the capacity that you want, then either would be fine, but I cannot speak for the SIP machine as I have no experience of them.
As others have mentioned, your main concern will be outgrowing the lathe, so just think carefully about the size of bowls/spindles that you might eventually want to turn.
Les