For the blues, I like B91, B93, & B95. I sometimes add B97 if I want it darker, but primarily use the lighter three.
Reds: R20, R22, R27, R29.
Pinks: R81, R83, R85. Add R89 if you want a nice burgundy.
Greens: G21, G24, G28 (think shades of SU garden green in tone) I also like G21 with G94
Blue Greens: BG000, BG01, BG05, or BG10, BG000, BG01 (the BG10 gives it a greener hue)
Purpley-Blue: B60, B63
Browns: E31, E33, E35, E37 (I often drop the lightest or the darkest marker depending on what I am coloring)
I need more yellows, and don' have a blending pair I like yet. I don't use orange much at all, so I'm no help there either.
You can see my non-updated color chart
here if you want an idea of the colors. I have a few in the 2 number apart range that aren't really that different too, and it is very annoying! I could have spent the money on a different color, KWIM?