My family has been in ponies for 40 years. Moderns are our primary focus because we find them much more engaging, intelligent, personable, willing, etc. Of course, we only show our bloodlines. We searched for an acceptable Classic for our children for YEARS because we couldn't find one that met our standards for personality, interaction, etc. Ponies vary by bloodline. You can't paint ANY one division with any broad brush. Moderns will have a lot more life ... because they are supposed to. All divisions will have animals that are difficult. However, as a whole, you'll find AMERICAN Shetlands some of the best all-around ponies in the industry ... nothing like the ponies we all remember from our childhood. One of my favorite all-time pics is of my four-year old daughter leading a Modern mare to the make-up ring in her bridle w/ head down plodding along ... about 5 minutes before she went blazing down the rail as hard as she could go - nostrils flared & eyes wild - on her way to her 3rd Congress Grand Championship.
FYI ... Shetlands have a MAXIMUM height of 46" but there is NO minimum height. They can be as small as you can breed them.