From personal experience and from speaking with families that have purchased male puppies from me I have found the following to be true.  As far as physical differences go we all know the male/female anatomy is different. Usually males will be a little larger than the females but only about 1 to 2 inches in height and 3 to 5 pounds heavier. But, this is not always true, our Striker is just 14 lbs., Bo weighs 16 lbs & both Raptor & Lync weigh 18lbs.   I have some females that weigh close to 20 lbs. & then others weigh right around the 15-16 lbs.     For the most part you will find it hard telling the difference of size between the two without looking closely. 

When you neuter your male puppy before he reaches maturity (around 9 months old)  he will not develop those “bad” traits that give the male dog a bad rap. For instance, he will not feel the need to hike his leg, hump or mark his territory. In fact most all males when neutered as puppies will squat just like their opposites and never lift a leg. He also will not feel the need to chase females in heat while he is out for his daily walk.  Believe it or not a female puppy will actually hump more then a male puppy, this is actually a puppy thing early on, some puppies go thru it & others do not.  If your puppy does this they will stop  either on their own or once they have been spayed or neutered.    A female puppy when spayed will loose a lot of her “bad” traits too.  You should have her spayed between 4-6 months old.  You really should have her spayed before she reaches her 1st heat cycle (around 7 months old).  Once you spay her she will not have a heat cycle every 6 months and bring the mess that comes along with it. A female in heat can be very moody & you will not have to deal with this once she is spayed. 

Now as far as attitudes go both are very loving and always ready to please, just as a Cocker Spaniel should be. :)   But one has the other beat hands down.  After raising Cocker Spaniels and having both males and females I have found a difference in their demeanor.  If I had to choose between the two, which I hope will never happen, I would pick a male dog every time. 
A few reasons for this I have found that the males are much more affectionate and loving. They are more outgoing and sure of themselves always showing a sense of confidence. They show little moodiness and are less prone to emotional swings.  A male dog is always eager to please his owner, he takes very quickly to children & is more accepting of other pets.   You can rely on the male dog to be your best friend & loyal companion in any situation & they will always be young at heart.  Female dogs can be emotional and sulk around if they don’t get their way.  The males just let it go and move on.   The female will be playful as a puppy but as she gets older she will tend to sit back & see what is going  on around her.  The males on the other hand are more playful and tend to remain playful even in their elder years.  The males love to be in the center of the action & become a huge part of the family.  The female is also the “QUEEN” she is the “BOSS”, she can have mood swings where one minute she just as sweet as can be right in the middle of all of the action & the next minute a little grumpy & wanting to be alone.  If you are wondering who is the boss around here, it is Demi.  She is a very sweet dog but yes she sure does have mood swings.  We feel very lucky that Demi allows us to live with her. :)  These are just a few reasons I tend to favor the male.

A couple of other things to consider is the cost of neutering is usually lower than spaying because the surgery is usually considered to be an easer procedure with a quicker recovery time.    Spaying a female is a little more extensive because they are removing the uterus, this is why the cost is usually more & the female does not bounce back quite as fast as the male.  Also the price is often lower for a male puppy compared to a female. The reason being is to give people an extra incentive to buy the male due to the misconception that the female makes a better pet.  I personally would pay more for the male characteristics if that were the case. :)

These were just a few thoughts on the subject and if you had your mind set on a female only, hopefully this has opened your eyes that a male puppy just might be what your looking for. Keep an open mind when selecting your puppy, don’t close the door on a puppy because of preconceived notions of its gender, because you may be missing out on the best companion that you could have ever had.   Either way you go male or female, if it is a Cocker Spaniel you can’t go wrong.  Just keep in mind every dog, male or female has it’s own personality & is unique in every way.  The differences that you see should not be based on the gender, male or female. The differences that you should be looking at should be based on the litter as a whole.  When looking at the litter you may see one puppy in a litter that is more outgoing, the 1st one to check out a new situation & the 1st one to figure things out.  Then in the same litter you may see one that may be a bit more reserved & tends to be more cautious when checking out a new situation.   Sometimes this is very hard for a common person to look at the litter & be able to tell the personality developing, that is where the breeder comes in, it is very important to accept any advise that the breeder is giving you & weigh all aspects.  Lets face it, who knows the puppies best besides their mother, yes the breeder.  I spend every day with my dogs giving them all attention.  I know what each one of my dogs like & what they do not like.  Every one of my dogs has a different personality, some may be very similar but each one is unique.  When we have a litter I spend many, many hours each day with the mother & her puppies.  I at least spend 2 hours a day just sitting & watching the puppies, observing who is the 1st to nurse, who is the last, how they sleep & where they sleep.  Of course as they get older I have other observations as well but this way I know my puppies (each & every one).  We love every one of our Cocker Spaniels and they are equally spoiled, although the males seem to enjoy the attention a little more in our Cocker home. :)
 

                                                                        Bill and Susan