Chickens are a bit like people.  You meet good and bad everywhere.  You did the research, and chose according to what you have read.  Now you're second guessing yourself.  That's normal, especially given how many wonderful breeds of chickens there are.  Looking at a hatchery web site or catalog is a bit like going into a candy store.  I have a neighbor who had a PBR go broody last summer.  The girl wasn't even a year old, but made a wonderful mother.  PP stated they love RIR.  My RIR is personable, however she is mean, simply because she is the alpha pullet, and considers it her job to be a bossy b****.  No body eats unless she says they can!  If you're still having second thoughts, you might consider contacting the hatchery and asking if you can change your order. 
 
If you want to change your order, and MPC will allow you to,  (It shouldn't be a problem, as the chicks that you'll be getting haven't even made it to the egg stage yet!)  my recommendation is to try several different breeds at once.  That way you can get a varied egg basket, you won't have a whole flock of chickens that look identical, and you get to evaluate several different breeds.  If you haven't already checked it out, review Henderson's chicken breed chart.  If you do a varied flock, look for breeds that are listed as docile.  That way, you're more likely to have a flock that plays well together.  If you're planning to breed chickens for your future generations, and it sounds like that is the way you're leaning, choose the rooster to match the breed you think you'll enjoy the most. 
 
Chicken ownership is a lot of fun.   As long as you do a little homework, you'll choose breeds that will work well for you.  And if you get that order in April, no matter what you end up with, you'll fall in love with them.  And even if you do fall in love with them, there'll ALWAYS be a little voice in your head telling you that you should also have a couple of such-and-such breed because they're so pretty... lay such a nice egg... have a good reputation for being...  and on and on it goes.  That's where chicken math comes in.  And that's why the hobby has such appeal. 
 
One more word of advice:  Don't believe the literature that says that chickens need so many square feet of coop and run space.  Especially, don't believe it when a manufacturer says their coop will house X number of chickens.  Happy chickens have plenty of space.  And if you're hatching babies, you'll need room for them!