The last time I saw a category in the Guiness book (1970s,) the most was avocado but it counted mostly calories. Least was cucumber which was basically just water. Any updates on this?
Avocados are probably the most nutritious they have a heap of vitamins and they have fat, carbs, and protein in them.
After reading labels, my vote for least nutritious is any fruit sold in a can.
Nutritious isn’t really a fixed quality, it’s relative to your needs. If it’s vitamins A and C that I’m needing, a grapefruit is a lot better than an avocado.
Didn’t Mel Brooks do a bit on exactly this? I think he said a nectarine.
Provided it’s not in syrup, how is fruit in a can different, nutritionally, than other fruit?
For the calories you take in (less being better) I would vote for both the Apple and Banana as the best fruits for your overall health. IMO of course, I have done zero research 
Berries are a very healthy, low-calorie fruit with blueberries topping the list.
Bananas are one of the highest-calorie fruits, so your premise is flawed.
Processing. In order to preserve canned fruit, it must be subject to a sterilization process, which is normally some form of high heat. This will break down some of the nutrients found in fresh or instantly frozen fruit.
Obligatory Disclaimer: IANAmedical professional, nutritionist, trained chef, etc. I have however engaged in commercial market gardening and read a lot ofcrop-related material from the local extension service and other sources. The received wisdom is that among fruits grown in the temperate regions apples are at or near the top of the nutrition scale. And one publication says that strawberries are “nutritionally bankrupt” (but very tasty).
Most nutritious fruit: The one you eat instead of a donut.
Least nutritious fruit: The one you buy because you “should” but that inevitably rots in the back of your pantry.
Eggplant is pretty low in nutrients.
It’s also not exactly what you mean by “fruit.” To a botanist, it means something specific. To a cook or a consumer, the meaning is a little more fluid.
Strawberries are high in vitamin C.
Dates seem to be pure sugar, but looking at the nutrition data at wikipedia they seem to have enough nutrients I doubt they are the worst.
Blueberries specifically are one of the few “super-foods”. So they might be the “most” nutritious, for various definitions of nutritious. Watermelon on the other hand has very few nutrients and is essentially equivalent to drinking sugar water, so I’ve heard.
Since Fruits Contain a Spectrum of Micro-nutrients, one can not Compare to Another as “better for you”… but, one can contain-for instance- more vitamin C than another.
Figs are Highly nutritious, but not ‘better’ than, say, Dragon Fruit or a Tangerine.
Eat a Wide Variety - many colors- to get the most out of it.
Try buying fruits in Ethnic Markets to sample some ‘new’ ones… Always WASH produce.
Fruits differ from Vegetables in that they’re not Self- Propogating. Many Fruits are called other things: a Tomato is a Fruit, but often referred to as a Veggie. (tomato belongs to the nightshade family, like eggplants). Quinoa is technically a Fruit, but it’s Nutrient Profile and Method of harvest & Prep is so similar to grains that it’s bundled into that category.
Despite any ‘failings’ you may see in a fruit- if it’s edible, fresh, and delicious~ it’s probably a great snack.
Citrus fruits (oranges, lemons, limes, etc.) are also high in Vitamin C. The British Royal Navy served limes or lime juice to sailors because it prevented scurvy. It’s now known that scurvy is caused by Vitamin C deficiency.
It’s true about the definition of “fruit”. Botanists consider true nuts and almonds (which aren’t true nuts) to be fruit. Many people don’t consider them fruit because they are so dry.
But God hates figs
Now in the morning as he returned into the city, he hungered. And when he saw a fig tree in the way, he came to it, and found nothing thereon, but leaves only, and said unto it, Let no fruit grow on thee henceforward for ever. And presently the fig tree withered away. And when the disciples saw it, they marvelled, saying, How soon is the fig tree withered away!
Matthew 21: 18-20
Which means it is high in *nutrients. *
But yes, many fruit eaters are looking for fiber, vitamins, and micro-nutrients, using fruits as a “diet food” not a source of nutrition/calories. In that case, perhaps blueberries, etc.
However, if the OP is looking for a “desert island fruit”, then Namcalb’s avocado is correct.
Actually, many canned fruits and vegetables have similar levels of nutrients compared to fresh; the reason? Fresh fruit/vegetables are often picked when unripe, thus have less nutrients to start with, while canned if often picked when ripe, plus fresh produce degrades pretty quickly:
(Yay for pizza for the last one, although of course pizza shouldn’t count as a serving of vegetables unless there actually is a serving, including other vegetables)
The salt added to canned vegetables is a much bigger concern (or perhaps not), or the sugars often added to canned fruit, but you can find them without salt or sugar (note, don’t drain the liquid instead, since many nutrients leach out into the liquid).