i look at it this way.... What is more comfortable, fitting 4 people into a 2 seat car or a 4 seat car. same works with ram. the more channels it has the smoother the system will run. Also some say it doesn't matter right now but look at the GHz of the ram, buy the best you can afford.
If this is for gaming...
Games right now will use 30-45%( at most) of 8 gigs if i remember right. Now are you going to be using team speak, add-ons, running multi monitors, watching youtube ect ect. may use up to 35-65% (based on my system and what i have running when i had 8 gigs)
Now if you plan to steam via twitch or other streaming sites you may want to think about bumping it up to 16 gigs unless you have or plan to build a streaming PC. For me just running the game. TS. OBS, a streaming assistant blah blah blah i was hitting around 60-80% usage. once i slapped in 2x8gig sticks with everything running i sit around 35-50% of usage.