Trike vs Sidecar
I think a trike would be an easier ride. With a sidecar you have to hold 'opposite pressure' most of the time to stop the bike from turning toward the sidecar, even if the sidecar is properly set up. (Everything depends on the slope of the road and the direction of the wind.)
Turning away from the sidecar, you can out-corner a trike but turning toward the hack, you have to be careful or you become a 2-wheeler again

I like my hack because I have so much storage space - more than the trunk of a full-sized car. The down-side is that your riding buddies will always be asking if you can throw 'this' or 'that' in your sidecar for them.
Both have their pros and cons. A trike will handle the same in left and right turns, but with a sidecar the handling is different between lefts and rights. Braking and accelerating are different too. I think a trike would be faster on a twisty road if pushed to the limits, but an experienced rider on a hack might be close.
As for needing to hold "opposite pressure", a number of sidecar companies (but not HD) offer electric camber control you can adjust on the fly, making it easy to hold the rig straight on cambered roads.
When it comes to cargo capacity, there's no comparison, sidecar wins by a lot.
Sidecars hold more of course, are safer I think for small children (I put a seat belt in mine for my grandson when he was 5), and depending on the model, can be a more comfortable ride for the passenger, though their visibility is limited on the driver's side. On the negative side, they get worse gas mileage - not the weight, they have a lot more wind resistance - and on some a sidecar windshield can divert air and rain at the driver. Trikes and hacks will both build shoulder muscles on winding roads.
At some cornering speed turning away from the sidecar, G forces will lift the drive wheel, and it can turn turtle forwards, most unpleasant for the driver, and worse for the monkey, if one is riding in the car. Some hacks will do this before they keep up with a trike. Also, if you like doing donuts, obviously that doesn't work well turning into the hack, but again, spinning too fast away from the hack, it'll flip over the car forwards. I almost found that out the hard way playing in snow... They might be more stable in turns from the car if the hack wheel was midships to the bike, but they're always set farther back closer the rear wheel. Put a lot of pressure against the hack side, and they rotate over the longer axis, between the front and side wheels. You don't want to do that.










