I grow several types every year.. like the qualities of both... heirloom for flavor.. but can't beat hybrid grape tomatoes .. sweet as candy and high yields

I grow both, but the decision isn't made whether it is Heirloom or Hybrid. When I'm shopping for seeds, the 1st thing I look at is the description of great taste. Then I choose the fruit size/type: Cherry, Paste, Slicing. From there I check out different colours and finally the choose between a vine(indeterminate) or bush(determinate). I don't base my choice on whether it is Heirloom or Hybrid.

There are a lot of great tasting Hybrids that have greater disease resistance and have prolific fruit production which I would choose over a Heirloom that is prone to cracking, bottom end rot or blight. It is very disappointing to have visibly healthy plant but with all the fruit affected with bottom end rot

If colour is the focus, the Heirlooms win. Chocolate Cherry, Yellow Pear, Purple Cherokee and Green Zebra are quite different and there are no Hybrids to sub for them.

I love the heirlooms for flavor and the hybrids for dependability, so I grow some of both. : )

I go along with Joanne on most points. It is unfortunately true that for many years plant breeders focussed on commercial factors to the detriment of taste, but to be fair the emphasis has change. F1 hybrid brussels sprout Trafalgar for example, described in the catalogues as "the sprout even your kids will enjoy!"

Team Both for me as well. We aim to grow enough to sell the extra. Hybrids are reliable producers toward this goal. And there are many hybrids available that cater to the small grower with taste and color varieties. The Burpee Honeybunch tomato that my daughter and I are in love with is a hybrid variety.
But we also like to save seeds, and hybrids can't be relied on to grow true. Heirlooms can. So we have fun growing both.

It depends...

For tomatoes, I prefer the heirlooms and open pollinated tomatoes. (I like the flavor and diversity and I can save seed.) This year I am growing 'Stupice', 'Foxy Lady', 'Purple Haze Homegown', 'San Francisco Fog', 'Clint Eastwood's Rowdy Red', 'Fireworks', a grafted 'Cherokee Purple', and a mystery tomato from seeds that I saved from a mislabeled (hopefully open pollinated) tomato plant that I got a few years ago (this is the first time I will have grown out those few seeds).

For peppers, I like a few open pollinated ones ('Corno di Toro' and 'Lipstick' are two of these), but the hybrid pepper 'Gypsy' is a very good variety for our area and is hands-down our favorite pepper for taste. It can take our cool nights and still produce well, and the peppers are equally good raw in salads, or roasted and served as a side dish.

I tend to lean towards Heirlooms because I like to save seeds.
But I do grow some hybrids as well.