Fleece rollers and auto testers, changing socks and manual testing are the bane of the hobby from my point of view. The release of these two items to the hobby made me enjoy it much more.
My Vortech pumps. As we all know flow is a huge aspect of a reef tank and with all of my older style pumps I was too lazy to clean them regularly. With it being incredibly easy to change just the wetside I am willing to do it frequently enough to keep my flow where it should be.
I like my fleece roller and it's integration with Neptune to turn it on and off to adjust Nutrient levels. With the addition of automated po4 and no3 testing I should be able to automate the roller on/off schedule similar to the Trident controlled DOS and 2 part.
I'm kinda old school and love skimmers. However, having reentered the hobby after a very long hiatus, I have to say the interconnectivity and ability to control various things like pumps, lights, etc. via wi-fi is something that has really come leaps and bounds.