It would be helpful for you to indicate region/ state you are in. I have lived in E WA, and Ohio - both in zone 6, and lived in zone 6A and 6B in Ohio. Each of these 3 locations has different, even though in Zone 6.
Overall, the EASIEST veg I've grown has been beans, green beans, or ones for drying, all have been easy and grown well. Soybeans included.
Brassicas (cabbage, brussel sprouts, etc) have more problems with bugs, and long grow season usually.
Lettuce can be good, but too hot and they hate it. Too wet and it is very dirty, needing a lot of cleaning.
Cucumbers - I have a lot of cucumber beetles, so many varieties succumb to wilt spread by the beetles, but some hybrid varieties do well.
Squash - takes a lot of room usually, but tends to produce well unless you get a vine borer and then you will have limited to no success. Summer squash, yellow or green varieties, tend to produce quickly and repeatedly.
Carrots take F.O.R.E.V.E.R. So, I plant among the beans and tomatoes so I don't have to watch them not grow. Eventually, the tomatoes produce and around then, I can check the carrots and might have some or need to wait a bit longer, but when cleaning out the bed in the fall will find some still good carrots. Plus they are known to be beneficial.
Peas, Fun and tend to be quick. Usually hate heat, can tolerate some shade. For me, they take up too much room for too little yield, so I would not plant them if I was limited on space.
Tomatoes. Yum, but can get large. So, if limited on space get a "Determinate" variety that is sold as a compact or container-friendly. Cherry types tend to produce a lot. If you want slicing types, then stick with smaller ones to get more in a limited space. We had great luck with "Compari" variety bought at a garden center last year.
Peppers: LOVE sun and heat AND water. Some produce better than others. Bell types for me have been lackluster bc they only produce a few per plant and then they are done (or the season is done for them bc days are shorter and less heat). We tend to grow Italian types, and have pretty good production, but some are better than others. We generally don't grow hot peppers, but those can grow well in pots, too.
Strawberries, you need to put them somewhere you won't disturb them for 3-4 years. First year they are establishing, the second and third years are best production. So, many will buy more strawberry plants year 3 and plant so that they are establishing and not producing that first year while other bed on year 3 is still producing well. Strawberries need to be moved after a few years due to disease usually, and for best production on younger plants.
