Larger capacity coffee and tea makers usually have a heater tube with wider diameter helping it against clogging and scaling.
Always check the glass jug whether it is thick enough as thinner glass is more probable to snap or break under high temperature.
It is hard to give any definite suggestion regarding compressor coffee makers as the key parts (tubes, valves, etc.) are in the inside and their quality cannot be checked without disassembling the machines. In general, though, it is safe to say that cheaper models from the Far East have gone through less research and development.
With most non-compressor coffee makers valve obstruction and scaling are often occurring problems. Only a handful of models make an exception thanks to some better executed details.