I like both males and females -- who wouldn't? :lol: but must say I prefer boys as well for the same slight differences.
Housetraining is going to be about the same. It varies more by individual dog, not gender, and results depend also on the degree of time and attention the owner puts in. Every accident is a small slide backwards and will delay success.
On the issue of neutering, personally I would never, ever, risk not neutering males, for so many different reasons (that is setting aside that most reputable breeders especially in the US home pet cavaliers on strict spay/neuter contracts anyway). My primary reason would be safety for the dog -- from seeing the ratio of unneutered males in the pound to either neutered males or females and seeing just how many darn males we get roaming around my neighbourhood every time a neighbour's bitch goes into heat -- I have NO idea where some of these males appear from, some obviously not remotely near our area as I have never seen them, and they become total pests, they FIGHT, and also wander around into the streets -- it is a nightmare and such a risk for the dogs. Some neighbours have taken these poor loose males to the pound -- safer than wandering around and a more humane death than being hit by a car.
When I worked in general rescue, at any given point about 75% of ALL dogs in the pound here would be unneutered males. :yikes Many of these were picked up in gangs, following some poor female in heat. So in other words -- lifting a leg is never the main reason I'd get a male neutered, and wasn;t for either of my boys -- keeping them safe as possible was.
The other issue I'd have with unneutered males is the level of extra responsibility for the owners -- some can handle this but most never even think about how they manage their intact male (if they were out walking an intact female in heat, they'd be a lot more cautious!). Too many owners let those males run off lead. Unless you are going to always keep an intact male on the lead, at arm's reach, there's a good chance that male is at some point going to get the chance to mate with a female in heat. It takes two to tango and the responsibility for yet another litter of unwanted puppies will lie just as squarely with the owner of the male as the female. And vets will tell you that many of the uneutered males they see will need prostate surgery by the time they get to be around 8-9 -- not a time when I'd be wanting to put a dog through surgery. This has been a real issue with a couple of my older male rescues -- they needed surgery, and needed a neuter to prevent the prostate problems worsening but they were of such an age that I felt terrible having to make decisions.