Studio monitors

Someone from KRK might shoot me, but...I think the only reason to get the 5 instead of the 6 is if either your space is really cramped, or you can't swing the extra $50 per speaker. But that said, I got a pair of 5s for the "kitchen computer" that I use for internet radio and watching Netflix. They're fine in that context - the space is cramped, and my budget needs to be devoted to sound in the studio more than the kitchen 
 
To be fair there are quite a few speakers in the KRK's price range that will do the job. The main feature of the KRKs is they're very flat. Some people don't like that, but there are bass and treble trims on the back if you want more push or sizzle.
 
[Disclaimer 1: Like Cakewalk, KRK is a Gibson Brand. Disclaimer 2: Gibson doesn't control what I use in my studio or home, but I use KRK VXT 6 speakers (mixing) and Les Paul 8 Reference Monitors (mastering) in the studio, with a pair of ADAM A7s for "let's test this on another pair of speakers."]
 

Look at the JBL LSR series

I upgraded to the JBL LSR308's.  A big improvement over the Samson Resolv 6.5a's that I had.  I used to have problems with bass on mixdowns, but not anymore.  The 8" JBL's fixed that.