Many tomatoes can be used in lightly cooked dishes like pasta primavera. When slow-cooked, they can be less predictable. A beefsteak releases more juice, for instance, so you may have to simmer a sauce longer to thicken it.
To avoid uncertainty, go with paste tomatoes. Paste tomatoes are drier and have more pectin (the stuff that makes jelly gel) to add body. They're also rich in the amino acids that contribute the savory taste, umami.
Plum (or roma) tomatoes, especially San Marzanos, are the choice here. Surprisingly, few plum tomatoes are actually plum-shaped; oval and oblong are more common contours.
Whatever the tomato, skin and seeds will add acidity, which you may or may not want. Also, some people find them unsightly. You might peel and seed tomatoes before cooking, or strain out the offending parts afterward for the desired texture and tang.
Our final tip is for tomatoes in the line of fire.