This topic comes up quite a lot - I did a lot of work for this working for my old club - it depends what you are after. If money is no object, then I think Kukri are really good, offering a fully custom service, so that your kit will be unique to your club.
If you're looking for good value, then it depends how many shirts you're after as different companies charge different set up costs.
I've always recommended Boundary Sports, who have always given me a top notch service.
The team I play for currently use Pro-Skins, which I believe is linked to Charlie French. The advantage with Pro-Skins is that they allow you to set up an online club shop where people can order individual items, as opposed to having to order a batch of 12 for example. They alos give 10% back to your club.