Shrubs 3 x 3' with a wow factor
Some of the small hebes are lovely......folage colour varying from red to cream to grey to shades of green with flowers.
Abelia Confettii.......check out this beauty.
Caryopteris varieties.....sterling silver has blue grey foliage topped in late summer with bright blue flowers. Also Summer Sorbet with same blue flowers but with beautiful yellow leaves
How about a couple of winter heathers like carnea, darleyensis and mediterranea all with winter flowers and some have winter foliage colour?
Not a shrub but penstemons are evergreen perennials with lots of summer flowers at about 3 or 4'
Some small dwarf conifers like juniperus blue star ....blue foliage and evergreen....planted with an orange echinacea, for example, will provide the wow factor
If you have acid soil check out kalmia, dwarf rhododendrons and azaleas.
For scent and attractive evergreen foliage look at daphne odoraaureomarginata
Check out santolina lemon fizz......butter yellow foliage