I agree with tigerdragon's comments. My system is low tech, but I love my apex. I travel a lot, and this has allowed me to monitor my parameters and turn off/on select pieces of equipment while away. I combine the apex with a cheap ($35) camera in my sump area so that I can watch what is happening with my equipment using my cell phone. On occasion my skimmer has overflowed, and my apex allowed me to turn it off until I got home and made some adjustments. Compare this to my friend who recently came home to 10+ gallons of water on his new hardwood floors. Also, I like the graphs of my ph and temp, as it has helped me fine tune my water parameters over the years.
As for which system is right, I suppose it depends on your needs. Due to a lightning strike, I have had two different apex systems. The energy bars are different sizes on apex vs. apex jr., so how many outlets you want to control? Do you want a ph monitor? The apex jr. doesn't have one standard (I have had both types of ph monitors, and the labgrade ph is well worth the additional money IMO). The regular apex also has additional capabilities like ORP monitoring and variable ports. There is a good chart comparing the capabilities on Neptune's website under "support /documentation".
If you are like me, you will eventually want most of the capabilities Apex has to offer even if you don't need all of those capabilities. You can start small with the jr. , and buy add-ons later, or you can save yourself money in the long haul and just buy the regular apex upfront.