Due to problems with Box blight and in box hedging and shapes, I would recommend any of the following as alternatives for new plantings.
However should you have an established box hedge that is suffering from box blight, we are happy to come around and discuss ways of controlling the problem ( you will never eradicate the problem but you can control it with careful pruning and the right chemicals).
Pittosporum - Pom Pom & Golf Ball
Both very similar, holds its shape well, softer growth, paler green / silver in leaf colour not so rigid as box, fairly tough but could be caught out by a cold period so would use it in a sheltered spot.
Pittosporum - Tom Thumb & Gold Star
Both have similar growth so again good alternatives just different colours!
Ilex crenata Dark Green
Very similar in leaf size but a darker green, slower growing hence they will be more costly size for size to box however very few known problems.
Taxus baccata (yew)
Nothing like box in appearance, however has been used as a box alternative and as a good hedging plant in its own right, good as a larger grown topiary bush but as a smaller topiary shape I would avoid as it is very hard to get a good shape out of.
Lonicera Tidy Tips
Good as a box replacement, very similar in appearance, very new to the market so not readily available yet but I think it will become very popular as it is much cheaper than Ilex to produce as it is much faster growing
More plants to follow