Partnership made it possible for me to start my path to ownership. The better half ("my business manager") would never, at first, have signed off on my owning 100% of a plane. But when I got to flying, and she got used to the idea of my being a pilot, buying out the partner when he lost his medical was not an issue. It was a "nose of the camel" deal.
I knew the plane, and I had known Wally Peterson for almost 30 years. When I got my license, he asked did I want to go halves with him in his Cessna 150. The Business Manager (after some discussion!) gave her assent.
He's a WWII vet, and a generation in front of me, so out of respect, I made it policy that I never argued with him. Never had to, actually. (He also had a Cub, so conflicts actually never happened.) Our one difference was that he usually didn't want to spend on any upgrades.
We used the in and out service of the local FBO, and our agreement was that when we got back, we'd have it topped off so the next to fly would not be paying for the partner's fuel burn. Of course this meant we were both paying for the gallons that vented onto the hangar floor.
The really bad part was being yoyo'ed: We were upset over expenses and were going to sell the plane (Damn plane! We should sell it!") then we liked the plane and were going to keep it, then back again to putting it up for sale, then... You get the idea. Of course, I could fly it until it was sold.
Now I get the plane out and in myself, I know it better -- we used to wash it once a year! -- now, I do some cleaning waxing, and buffing after every flight. And I'm prouder of my 150 when I land somewhere.
My former partner is the salt of the earth, and splitting expenses was good, but having been both places, I won't go back. Now that the business manager is used to my being an aircraft owner, I only have one person to convince about expenditures. And my Cessna 150 is NOT FOR SALE.
Bottom line: even with the most agreeable partner in the world, owning is better.