Z-Cat,
The simple truth is they are all horrible. Every single one. All are high in fat and sodium, most are tasteless and do not resemble sausage in any significant way. Avoid them at all costs.
That being said, I too have succumbed to a sale on these nasty bits, as an exercise of nostalgia. They were big in the 50's and 60's when everyone was afraid of undercooking pork.
The major brand then was Brown & Serve and it is still around. If you must try this sort of thing go for the turkey sausage as it has the least fat and best flavor.
I still do not recommend eating any of this stuff. When I buy a box, I know I am not buying sausage, I am buying nostalgia. Believe me, real sausage tastes a lot better than nostalgia.
If you must do precooked sausage, I suggest Johnsonville Stadium Brats. They are large well seasoned sausages that you can sink your teeth into. Yes, they are fatty but in this case the taste merits the fat. I usually have them for lunch as one would do a hot dog, but they can cover breakfast as well.
By all means, buy real breakfast sausage. They cook about as fast as the frozen crud and are so much better in every way. Just don't cook them to death. Pork is safe at as little as 140 degrees, so use a light touch and you will have a very juicy and tasty result.