I've been in a partnership where we had 3 different airplanes over a period of some 5 years, and I've been sole owner of my current airplane for 9 1/2 years. Guaranteed, I'm a lot happier with my sole ownership.
My partnership started out with 3 partners, me, a doc, and a university professor, back in the mid-70s. We had similar flight experience except I was also a CFI, and we got along pretty well. Our agreement was that business flights took precedence; otherwise, if any of us wanted to take the airplane for more than a flit around the area, we had to give the others 2 weeks notice. We charged ourselves hourly based on projected maintenance and operational costs, each being separately responsible for any non-insured damages. The first airplane was a very nice low hour Skylane.
The professor sold his share after a couple years to another professor, and all remained well. Then when that professor decided to sell, the doc and I bought his share, so there were just the 2 of us. Things got a little tighter, but still manageable financially.
Things still went well, until the doc got the "need for speed". I could afford half the Skylane, but nothing more, but he suggested that we change the percentages so that I owned 1/6 and he owned 5/6, and we traded for a brand new TR182, pretty close to the first one Cessna built. Predictably, he became somewhat possessive, and he would get irked whenever I wanted to take the airplane even for a weekend. And he expected me to maintain the airplane, which meant I spent a lot of time flying it to Casper and back for warranty maintenance, because as delivered it was a piece of junk--whoever bought it after we traded it off got a good airplane, though, because all of the avionics and half of everything else had been replaced.
We traded the TR182 off on a T210 after a couple of years, and again the percentages were changed, now to 1/12 and 11/12, and it became hideous. Hourly costs were more than 4 times what the Skylane had been, which took a lot of the fun out of flying. Now he wanted a month's notice when I took the airplane for more than a weekend, and things came to a head when I gave him some 6 weeks notice, took the airplane for a week, picked up a rock during a run-up and nicked the prop, and when I got back, I got reamed--and he insisted that I pay to file the prop, whereas in the past, the airplane's account had paid for anything of that nature. When I reminded him of the flatted tires on both the Skylane and RG he had caused trying to make shorter roll-outs, the 2 months down time when he left the Skylane at a ranch strip and a herd of cows used it as a rubbing post, etc., he blew up--and I said, "fine, we're done--you can have my share, just get me off the loan". Somehow we remained cordial, but our close friendship became no more than an acquaintanceship.
For the next 25 years or so, I rented. Admittedly, my flying suffered, and there were times when I flew very little--the worst was going from biennial to biennial without any flights in between.
Then 9 1/2 years ago, I inherited more than enough to buy my airplane, a 63 P172D with a Lycoming conversion, outright, so I have no loan payments. It's not very fast and it won't haul a huge load, but it's mine. Soon after I brought it home, the engine threw a rod, and while it was down for the replacement engine, I had it updated with modern electrics and other things--and that began the series of changes and mods I've had done to it ever since, things which make it mine. Of course, that also makes it one of the most expensive older Skyhawks out there, but it's truly my airplane. I don't have to justify to anyone other than my wallet at the time if I want to do something. It's well-equipped, fun to fly, and it's mine. Oh, did I mention? It's mine.

The only downside, obviously, is that the bills are mine, too.
So if I had to make the decision for you, I'd say, get your own. Get what you can afford, even if it doesn't fit every mission you might have--but you can always rent for those occasional 4-up missions, and meanwhile, you'll be flying.
Cary