You have Glass sliders .... Bottle neck sliders ... Copper Sliders .... Metal sliders ... (some are layman terms because i dun really know the correct names for them)
But from my experience .... Glass Sliders are less responsive than Copper sliders ... the shinier metallic ones are the most responsive.
But too responsive can also mean one thing .... it makes you get out of control. Hence for my, a GLass Slider is just enough .... but i broke my glass slider all the time ... so currently i possess a Copper slider.
It sounds not too brighty and gives just the right responce to my picking.
Why ask about sliders? You trying to play Bluegrass?