Our best-reviewed stovetop tea kettle, the Medelco 12-Cup Glass Stovetop Whistling Kettle (Est. $10), is made of thermal-shock-resistant borosilicate glass, the same material you'll find in glass ovenware -- in fact, it looks just like the coffee carafe you'd expect to see in a diner, but it's safe to use on the stove. Users love being able to see what's going on inside the kettle (or when it's time for a good vinegar cleaning to remove mineral deposits from your water), and you can use the Medelco kettle on most stove type (it won't work on induction stoves), although if you're using an electric coil range you must put the included metal heat diffuser between the burner and the kettle.
Users say that water boiled in this glass kettle tastes clean and clear, with no off tastes; and, since it's not made of metal, there's no chance of it rusting. The only things some owners don't like are that you have to take the lid off completely in order to pour, and make sure you remove the plastic lid before you pour boiling water; otherwise, it can melt. The directions suggest that you should only use this kettle up to medium heat, which means it heats slower than metal kettles. However, we don't think that's a deal breaker because, if you actually read the directions, quite a few stovetop kettles tell you to moderate the heat levels. Also, you should be aware that if you use this kettle over a too-large burner, the handle will get warm; position it on a smaller burner with the handle outside the burner's radius, and it'll be fine.
Overall, users are thrilled with the novelty and good looks of this glass tea kettle, not to mention that it only costs about $10. The whistle is pleasant -- one user calls it "breathy" -- but not very loud, so you'll want to stay in the same room with this kettle. We also found quite a few users saying that they love this kettle so much, they were quick to replace it if they dropped one or accidentally set it on a cold countertop (which can crack the glass if it's coming off a hot burner).
For another classic take on the stovetop tea kettle, consider the OXO Good Grips Classic Tea Kettle (Est. $40). This classic, wide-bottom design is sturdy and heats up quickly, with a hinged handle that can be flipped to the side for storage or to fill the kettle, but stands upright while the kettle's on the stove. Users really appreciate the silicone touch-points on the spout lid and handle to protect you from heat, and they say the whistle is soft enough not to wake late sleepers (although in our experience, that means you have to stay in the same room as the kettle). The spout pours easily and doesn't dribble -- a real high point for a lot of users.
However, like most stovetop kettles, this one has a few quirks. You're supposed to empty it out and remove the lid after every use to prevent rust (this is typical of OXO kettles) and, because of the spout design, you can only fill it about halfway -- so its capacity is less than it might appear.
OXO also manufactures the excellent brushed stainless steel OXO Good Grips Uplift Teakettle (Est. $50) (it's also available in a polished steel version). We found some mixed feedback on this kettle from users who wish they could leave water in it overnight (you're supposed to empty it after every use), or who say the hinges on the handle come apart and that an extremely hot stove can even melt the plastic cap. But when the handle does work, users are in love with this kettle. It's an especially great choice for arthritic hands: Picking the kettle up automatically flips the pour spout open, and putting it down flips the spout closed. Its relatively gentle, multi-tone whistle alerts you when the water boils, and users also say the angle of the lid/spout makes it harder to overfill this kettle.
The KitchenAid KTEN20CB 2-Quart Kettle (Est. $40) has another take on the OXO Uplift's C-shaped handle. But the KitchenAid kettle's handle and lid are not attached, so lifting it does not automatically open the spout; you need to use your finger (or your other hand) to tip the lid of the spout open. Users like that the lid stays open once you flip it up, though, so you don't have to worry about holding on through the rising steam; and they like this kettle's whistle, which starts soft and builds in intensity until you can easily hear it in another room. The bright colors -- it comes in nine different finishes as of this update -- and classic look of this kettle is another high point.
That said, the KitchenAid KTEN20CB kettle does have some reported durability issues, including a plastic hinge on the spout lid that will melt off if exposed to too high a gas flame, a tendency to rust around the lid, and a tendency for the enameled exterior to chip and scratch easily. If you read through the manual carefully, you'll also see that if you leave this kettle standing on a hot glass cooktop, it can fuse to the glass. Users also say, however, that customer service is good about honoring their lifetime warranty.
No matter which type of stovetop kettle you use, be careful not to overfill it. If your kettle isn't marked with a "max fill line," leave at least 1/4-inch air space below the bottom of the pour spout or the bottom edge of the lid. This protects the lid seals in the kettle, which in turn protects its ability to whistle, and also keeps you from being splashed by hot water bubbling out through the whistle hole in the lid. Most users say they love being able to walk off from a heating stovetop kettle, confident that they'll hear its whistle when the water boils; but an overfull kettle will whistle more quietly than usual, or in some cases stop whistling entirely if the lid seals become damaged.