The thing that decides everything: they all brew the same
Buy the KBGV Select unless you have a specific reason not to. The KB makes identical coffee for $30 less without the automatic drip stop, the KBT swaps the hotplate for a thermal carafe, and the Cup-One is the single-mug version of the same brewer.
Every full-size Moccamaster uses the same copper heating element, holds 196 to 205 F through the whole brew, fills a 40 oz carafe in four to six minutes, and is certified by both the Specialty Coffee Association and the European Coffee Brewing Centre. That is true of the $339 KB and the $405 CDT Grand alike.
So the coffee is not the variable. You are choosing a carafe, a brew basket and a capacity, and paying between $260 and $405 for the combination you want. Anyone telling you the expensive Moccamaster makes better coffee than the cheap one is describing a difference that does not exist.
This is unusual and it is worth saying plainly, because in most brand ranges the money buys a better cup. Here it buys convenience and a different way of keeping the coffee hot.
How to read the model names
The letters are the spec sheet. K means the machine has a hotplate, with two settings at 175 F and 185 F. B is the rectangular brewer body, and CD is the cylindrical one. G means the brew basket has an automatic drip stop, so it closes when you lift the carafe out. T means a thermal stainless carafe instead of glass, which also means no hotplate. V is the volume selector on the KBGV, and S means the shorter body, 13 inches against the KBGT's 16, with a 1 L carafe rather than 1.25 L.
Read that way, KBGV Select is a hotplate machine with an automatic drip stop and a half or full carafe switch. KBT is the thermal version with a manual drip stop. KB is the plainest full-size machine there is. Once you can decode the name, the range stops being confusing and the price differences make sense.
The four comparisons people get stuck on
KB or KBGV Select. The KBGV costs $30 more and adds two things: a brew basket that closes itself when you lift the carafe out, and a switch that sets the machine to brew half a carafe or a full one. Its hotplate also runs on an independent heating element rather than the KB's hi-lo switch. Otherwise the two machines are the same object, both 40 oz, both 1475 W, both 14 inches tall. If you brew a full pot every time and never pull the carafe mid-brew, that $30 buys you nothing.
KBT or KBGT. Ten dollars, one feature. The KBGT's basket closes automatically when the carafe comes out, the KBT's has a lever you move yourself. The difference worth checking first is not the drip stop though, it is height: the KBGT stands 16 inches, the tallest machine here short of the CDT Grand, against the KBT's 15.25. Measure the gap under your wall cabinets before you decide, because on this pair the clearance is the more likely deal breaker.
KBT or KBTS. The only pair where the carafe itself changes. The KBT and the KBGT use a stainless carafe lined with borosilicate glass, and the KBTS uses a double-walled stainless one. The KBTS is smaller in every direction as well: 1 L rather than 1.25, 13 inches tall rather than 15.25. It is also $10 cheaper, which is the wrong reason to buy it. Buy it for the height and the smaller pot.
KBG or KBGV Select. The KBG is the machine the KBGV replaced. Moccamaster's US range no longer lists it, European retailers still sell it as the KBG 741 Select, and what the KBGV added is the half or full carafe switch. So a US listing for a KBG is old stock, and the real question in front of you is whether that switch is worth the price gap on the two listings you are looking at.
Glass and a hotplate, or thermal
This is the choice most people should spend their thinking on. A glass carafe sits on a hotplate that holds the coffee at 175 F or 185 F. It stays hot indefinitely, and it also keeps cooking, so a pot that has sat for an hour tastes noticeably flatter and more bitter than the first cup did.
A thermal carafe has no hotplate under it. Coffee brewed at eight in the morning is still drinkable at ten, and it tastes like coffee rather than like something that has been stewing. The costs are real though: you cannot see how much is left, thermal carafes need proper cleaning or they go stale-smelling, and they pour more slowly.
Two numbers off Moccamaster's own spec sheets sharpen this, and one of them cuts against the thermal carafe. The carafe is rated to hold the coffee's quality for up to an hour, not for the whole morning, so the honest version of the thermal case is that it stops the coffee cooking rather than that it keeps it good indefinitely. The second number is how the machines shut down. A glass model runs its hotplate for 100 minutes after the brew finishes before it powers off; every thermal model goes dark after about 12, because there is no hotplate to run.
Our rule of thumb: if the pot is gone within half an hour, take the glass and enjoy the hotplate. If you brew once and drink across a morning, take a thermal and accept that the second hour is a compromise either way.
What $369 does not buy you
There is no timer and no clock on any of these machines. You cannot set it the night before and come down to made coffee, which is a thing that $60 supermarket drip machines have done for thirty years. It is the complaint owners raise more than any other and we think it is a fair one.
There is also no grinder, no app, no cold brew setting and no water filter. The spray arm is a single outlet rather than a full dispersion showerhead, and some owners give the bed a stir partway through to even out the saturation.
What you are buying instead is a machine assembled by hand in the Netherlands, backed by a five-year warranty and a parts supply that means a fifteen-year-old Moccamaster gets repaired rather than replaced. Whether that trade is worth $369 depends entirely on how long you intend to keep it. Over two years it is poor value. Over fifteen it is very good value indeed.