Whaddya mean, you don't want duals? Come on, use both sub pre-outs
Yes, placement is important but multiple subs can counter the room's modes somewhat better than even careful setup of a single....but depends if you care about any other than your own seat to an extent. Don't think your avr particularly provides for separate setup of two differently placed subs, tho (does it allow separate level/delay for the different sub pre-outs?). Using two equidistant subs can work, tho.
Subs like those just made me want more.
How big is your room? Listening levels in spl?
Without any more info I'd tend to the Hsu myself but none of them are that far apart from each other to matter much otoh.