If you're looking for the best GLASS heater money can buy, Ebo-Jager are bar none hands down the best there is. They are made with thicker glass and triple-sealed (rather than doubel sealed) to insure water resistance and durability. I just recently discovered these, and as an engineer, am very impressed with their design. Someone did their homework!
However, the other heaters mentioned are also fine products, and a bit less money. It's probably not really necessary to have the triple seal, but the thciker glass does make it harder to break it from an accidental jolt.