Fix the slider. Call customer support and they will probably send you a new one for free. I can't tell what brand you have, but Delta, Grohe, and Hansgrohe will all definitely replace that free of charge. Be aware that the slider bar may or may not be the same brand as your valve.

The brand is Kohler - ideally we don’t really want to keep a slider. Are you implying that it won’t be very feasible to put in a shower head where the water flows from the top of the “bar”?

Your second and third pics are plumbed differently from what you have. There is no simple conversion to them that won't retire you to tear out tile and re-plumb. Take the advice you've been given above and fix what you have. Otherwise, plan on a remodel.

The water doesn't flow from the top of the bar, it comes from the outlet just above and to the right of the valve. Why don't you like a sliding bar? It gives you a fixed head and a hand held all-in-one. I don't see any downside to it. If you don't like the particular showerhead that you have, it is easy to swap that out for one that you do like.