You've essentially got 4 choices
XC50-230 - optically great, lightweight, but plastic construction, doesn't feel substantial but images are good - s/h from £100 upwards
XF55-200 - built like a tank, optically great, a useful piece of glass, bokeh can be a bit busy at times - s/h £360 upwards
XF50-140 - again superbly made, optically very very good, not light - weathersealed - can be used with teleconverters - s/h from £850
XF70-300 - its new and shiny and no-one has one yet! Looks excellent, has weathersealing, £729 on pre-order
I've had the first 3, in that order, still have the 50-140 - that said I changed because of some project/work requirements, and if just shooting generally would be happy with the 55-200