"Most attention" for me has usually been situational. I got a lot of attention in one of the last versions of the Ford Thunderbird, but that was because I was driving it around before it was available to the public. The perks of being an exhaust development guy back then.
As for stuff I've owned, I rode my 2000 Ducati 996 to work one morning. I always tried to get out before the school bus came but on this day I cut it a little close and the kids were already standing around waiting. For whatever reason some of them were very interested in the bike when in the past it was mostly ignored. I even thought maybe something was wrong?
I mentioned it at work and someone asked me if I had seen "The Matrix Reloaded" yet? I had not. When I did it all made sense.
My '66 Mustang convertible got attention. A couple in a Range Rover parked next to it one day and as I was walking towards the car I heard the guy say "...but they are so dangerous" as she was looking at it. Right about then she saw me walking up. I wanted to say it was a tank compared to my other toys but just smiled and nodded instead. She looked embarrassed...
My '74 750GT got a lot of attention, but only from a certain crowd. Bought it for $700, spent a little over three years rebuilding it.
I suppose though the one that got the most attention in general was my 907ie.
Early 1991, Ducati was just beginning it's "comeback" and not many people knew what it was. A lot of people who had heard of the brand thought they had gone out of business. I don't think it was particularly attractive but it was different. And the red... holy cow the Italians can do red like no one else. If the clouds were just right it almost looked like it was glowing.
I stopped for lunch one day and parked next to a red Corvette. When I came back out the Corvette owner was standing there staring at it. He told me "I thought I painted my 'vette red, but.... damn..."
I've had bikes I've liked better than the 907 but it probably has the most stories of any of them. Not long after I bought it the 900ss was reintroduced and was much more popular. The 907 seemed like a forgotten step child as the years went on but it turns out it had a following. I took it to a vintage bike show that was featuring Ducatis and I was surprised at the attention it got. It even got into a magazine.
It ended up being a garage queen so I finally sold it. It had a lot of sentimental value but I haven't regretted getting rid of it - it's been through three owners that I know of since then and is still sporting the same tires it had on it when I sold it, so no one else is riding it much either. One of the new owners tracked me down to see if i wanted it back.... Nope.
The 996 on the other hand??? Kinda wish I had kept that one, I kept track of it for a while and if someone offered it up to me now I might have to consider it... I owned it for 17 years, put a little over 7000 miles on it. It was the worst streetbike I ever owned. SUCKED in traffic or around town. Under 25mph you had to slip the clutch, but the flip side to that was it'd do about 70mph in 1st gear. And when the situation was right for it? Dang... I've had faster/more powerful bikes but nothing that ran as well as that one. Something about it was just right. As long as you didn't care about speed limits and that sort of nonsense. In 30+ years of this stuff it's the only bike I'd think about buying back. But it would have to be my old one. I told the last guy who bought it that if he ever wanted to sell it...