Hardest work small to medium breeds

[Doggieconfused]

Please tell me what they are so I can avoid them when choosing a breed! (I know all puppies are hard work but I’ve heard some are worse than others...)

We have a 10 month old lagotto who is the love of our lives, but DH has spent HUGE amounts of time training and walking him. He's a delight when out adventuring with us, and sticks to DS like glue in the bush, swims brilliantly, etc, but he takes a huge training commitment, because he is so bright and needs to have purpose. He looks like a teddy bear, but has BC energy. We live near a dog park, and he's always attracted to - and gets on well with - herding dogs. The breed also have a tendency to anxiety. And an incredible attraction to water and mud.

We would definitely love to have another gotti though, because we were prepared to work hard with ours, and he's definitely worth every minute.