Bookshelf speaker pairing with subwoofer

The list is getting pretty long.

My last small speaker was the Revel M106 and before that the PSB M2 and the Studio Electric M4 is much more enjoyable.   I can't say enough good things about the M4.   Great speaker.  

From experience in my home office, you'll get the best match between bookshelf speakers & subs by having sealed/acoustic suspension bookshelf speakers.

I can think of 2 brands off the bat that I know work well:

ATC: SCM11 (smaller) or SCM19 (larger). If you can fit the SCM19, that's it

NHT: The C-3 would do the trick

I don't have a lot of experience with a variety of bookshelves, as My ATC SCM19's are my first. I will say that sounded before I added a bass array.

Now they are fabulous.

Sealed speaker with three subs.

Why limit yourself to bookshelf speakers? There are slim floorstanders that have a similar size footprint. The advice to seal the ports is solid, better still is buy sealed speakers. You obviously intend to use subs which is the best way to get great sound but they should be sealed too. A ported sub is a lot more difficult to blend in and if you don't have variable phase then almost impossible.

A port resonates at just one frequency and there is no way to tune short of changing it's length, it's another invariant bass source and just presents problems.  With sealed speakers and sealed subs, which must have variable phase you'll be able to position the subs almost anywhere and dial them in for a nice smooth response. It helps to measure the room. REW and a microphone will get you there.

I hope your RELs don't only have 0 - 180 phase switch because you will spend all your time trying different placings.