None of those. Unless you do classic get something that goes down below 40Hz. If you buy one of these toy 5" monitors your low end most likely will ALWAYS suck.
My amateur conclusion after having a number of different pairs of monitors (HS50m, HS8, 305p, 306p, Rokit 5, Rokit 8). I felt I missed something with each and every single one of them. Yes they sound good in their range. None of them have deep enough bass extension, none of them sound "complete". I never learned how to mix bottom end because with all of these I NEVER HEARD IT.
So here's my decision: MO MORE little monitors. They look and sound cute, but you can't be serious about your mixing if you simply can't hear crucial frequencies of bass at all. With this 5" nonsene you will have ZERO information about your bass. You can buy a $2000 5" Genelec and you will still have zero information about bass to make mixing decisions and that bass will ruin your mix every single goddamn time. No "I'll add subwoofer later" nonsense, you won't set it up right most likely for even response, most likely you'll end up withsomething like +8/- dB in the sub range.
If you buy some crap cheap 8-10" monitor that does go to 35-40Hz and even if you have a crappy room you still have a chance of figuring it out where your bass is by using reference tracks, something like Sonarworks and just becoming familiar with their sound. Even the most poorly presented information is better than no information and blind guessing, and you'll be blind guessing 100% of the time with that 5" monitor nonsense.
5-6" monitors are waste of money and so are most 8", actually. Get a full spectrum monitors. "Buy cheap buy twice". You may be happy with 5" at first, but in a little bit you'll hate not having a full bass response. If you're short on budget look for used HR824 or VXT8 or ASP8, they can be had for like $500 pair at Guitar Center. Because if you're serious about you music you'll end up buying them anyway, just later after you realize how disappointed you are with those toy 5" monitors.