How long term are you looking for?

I have been using both of mine for about 18 months- and they both work very well still.. Any longer than that, someone else will have to pitch in!
As for maintenance and reliability they need the same sort of maintenance (all dosing pumps do!) and with regards to accuracy? Well, the Red Sea one is the winner here- but we knew that form the specs already. I calibrate both every three months or so- with the Kamoer being a fair bit off every time unlike the Red Sea.
For me, these two dosing pumps serves slightly different purposes.
Any reason why these are the only two you're looking for? If you need 3 dosing heads, I would look for a doser that serves that purpose! There are many, many makers out there!
Reef Factory is fairly new to the American market. They have a snazzy little 3 channel doser with software to die for. Have a look at that as well!