I'm moving from Vandersteen Quatros with built-in subs (great speakers, BTW) to small monitors (probably Harbeth P3Esr) for aesthetic and flexibility purposes. As I test these little speakers out I am less inclined to get a sub, at least right away. I think I'll enjoy them as-is for a while, and reassess later the issue of the sub.
So, you might just get a good pair of monitors, and just listen for a while. Setup/positioning will change how they sound, so experiment a bit.
If you need a sub later, go for it, but you may find you don't miss it after a while.
Of course, I am generally listening to jazz and vocals and not at earsplitting levels. If you are cranking up some rock, well, you'll probably want a sub.
I can't recommend one since I have not looked hard at them yet (and may not).
Good luck with it.