Thanks for the great info Sazbaby and Sydney Acres! In our flock we have two Silkie Roosters we use for breedinot for protection thats why i was asking. Our dogs are not the problem actually our dogs love to lay out there by the chickens and watch them like a rooster!! but we have people that dont to a great job of keeping there dogs under control... which might take all the chickens.

What would you recommend for the best breed of rooster?
That's really hard to predict, and depends highly on your specific situation.
Would you be keeping the protection rooster with your silkie hens? If so, then the rooster needs to be appropriately small, and the offspring will be mixed breed chicks.
Will you be keeping the protection rooster with your Silkie roosters? If so, he will likely become the dominant male, and may bully or injure your Silkies. Also, roosters that are bullied may become shy and have fertility problems. How would that affect your efforts to breed Silkies?
Do you have small children, or other people in your household that don't want to be attacked by a rooster? The most protective roosters are also most likely to be aggressive to people. Conversely, the sweetest roosters to people aren't always the best protection for the hens. The ideal rooster has judgement, but that's something that isn't always paired up with aggression.
If you get an aggressive game breed, he may kill your Silkie roosters. A game breed mix might make a good flockmate and a good protector, but you won't know until you try it. And the consequences could be severe.
I don't know which breed will be best for you. No one does. If I were in your situation and had decided that getting a protection rooster was the right thing to do, then I would start looking at breed standards for the various varieties. I would choose a breed where the typical rooster was no more than one pound heavier than your Silkie roosters if you plan on keeping them all together. Hopefully that will keep them from crushing the Silkie hens during breeding. Once I had that list, I would eliminate anything that has a reputation for being highly aggressive or overly gentle. Then I would eliminate any breed that is likely to have any limitations to speed or agility (i.e., short legs or excessive bulk at maturity). Once you've got your list narrowed down a bit, see which breeds are realistically available to you from the source you plan to use (you're not likely to find an Ixworth, even if it's your first choice). Once you have a reasonable sized list, then look into the characteristics of each breed. Which one(s) do you like? Remember, even though you're getting this bird for a specific purpose, you still have to live with it. Get a bird that interests you, whether it's based on personality or physical characteristics or color or whatever. But remember, breed descriptions are just averages. Individuals can be quite different than averages. I know a few stupid Poodles, several calm Labradors, and a whole lot of really sweet Pit Bulls, despite reputations to the contrary. Chickens are just as individual. Are you prepared to keep the rooster, or get rid of him, if he can't do his job properly?
Wish I could help you further, but there's just no right answer. Start with a breed that has a reasonable chance of doing the job within your specific limitations, that you can easily obtain, and that you really like. If you don't want to start with chicks, you might put up a notice at your local feed store. There's always people who are looking for homes for extra roosters. Sometimes seeing what's available, then determining if it might fit your needs, is a shorter search.