I've had a Hamilton Beach glass electric kettle for many years, and have never had any issue with buildup. I do clean it out regularly, and use Brita filtered water, so maybe that helps. My old Proctor Silex plastic kettle routinely got buildup on the metal coil.

I have hard water and don't like the look of the scale. I also don't like the breakability. I prefer the Cuisinart kettle that allows me to set the temperature I want the water to reach. There are six different temperatures to choose from.

https://www.cuisinart.com/shopping/appliances/tea_kettles/cpk-17p1/

I have one and also have hard water. I like being able to see the level of “boil” of the water.

Yes, I sometimes do a vinegar cleaning for mineral scale. But honestly, if scale is an issue it isn’t because you have glass vs. metal. You are getting it wither way and at least with glass I know when to clean it. (It would still be there with metal, just not visible.)

I had one for a long time and never had issues with it being cloudy. But I also don’t have hard water. I think that will be the biggest factor.

Do they stay looking relatively clear, or do they get scale or buildup? I think they look nice and that it might be helpful to see the water if I want to stop it just before boil, but I don't want one if it's going to look old quickly. TIA!!