Best powerhead to use

Sure there are downsides to koralias. i found that with age they seem to slow down in the respect they dont push as much water. I found that this happens in a relatively short amount of time. and i dont mean from the getting dirty and clogged up. I thinj it may have something to do with the way the impeller and the impeller shaft is designed. Sometimes if you turn the pump off for whatever reason (cleaning, water change etc...) you will notice that you have to push the impellor in down the shaft to get it turning. So Id assume that the design allows the impeller to move up and down the shaft while rotating which will cause stress on the motor and make them slow up after time. (just my theory) The other downside is that unless you buy the hydor wavemaker and matching pumps you cant run the normal koralias on a wavemaker. Its also kinda a rip off for that controller anyway so if you are gonna spend that much $$ on a wavemaker and pumps might as well get a nicer system.
Anyway, all pumps and wavemakers have their ups and downs so its more about weighing whats important to you and what you are trying to achieve within your budget.