A couple of days ago I was in an Italian deli and noticed they had several different brands of tuna in olive oil. I've been eating a lot more tuna recently, so I bought three small (80-100 gram) cans with pop tops to hold a tuna tasting at lunch.
The three brands were Flot from Sicily, A's do Mar (Portugal?), and Genova (which appears to be produced in the US). All three listed their ingredients as "tuna, olive oil and salt." The Flot and the Genova were labelled "solid light tuna in olive oil". The AdoM label was in Italian, so I'm not sure if "trancio intero" referred to the style/cut of the tuna.
Flot -- lots of oil, tuna uneven in color; darker, fishier flavor, more cottony texture. Slightly reminiscent of cat food.
A's do mar -- moderate oil, firm looking, even color; good mild flavor, almost sweet, very dense.
Genova -- no oil on top at all!, color light and texture somewhat flakey; slightly saltier, with a more pronounced olive oil taste.
For eating straight out of the can, the AdM and Genova were much more to my taste. The Genova had much less oil floating on top but the most olive oil taste -- perhaps the tuna absorbed more of the oil? This would be my choice for popping open a can at my desk.
I thought the AdM was the highest quality, both in flavor and texture. I think it would work well in salads and other preps where the tuna is the main ingredient.
The Flot didn't appeal to me at all. Still, the strong flavor might work well in a hearty sauce. Otherwise, I don't think it merits the premium price (although I believe the small can I bought was mismarked).