In terms of leveling/casual content, it's wise to know what your group needs (especially in a DF setting). If you can get away with less HP and provide more group DPS, then Slaying is a perfectly viable option. If your healer can't keep you alive or if you yourself are new to the content, then stacking a bit more VIT can help with that. Both accessory choices have their advantages and disadvantages - when I leveled to 60, I took any STR jewelry from MSQ, rolled Need on Fending accessories, and rolled Greed on Slaying. Whatever I ended up getting I used. It's important to remember you can change gear any time you're out of combat, so if say full Slaying isn't working for you then throw on some Fending after you wipe.

The biggest problem with the full Slaying meta bleeding down into casual content is that less HP + bad tank = squishier tank. Ideally what people need to realize is that Slaying is an option and, while it has advantages, it also has disadvantages. Back in ye olde 2.0 the STR tank meta was so small that people generally recognized it took skill to wear those accessories, but now that it's become more mainstream it seems like something anyone can get away with. Unfortunately there's no way to fix this problem outright unless SE steps in and gets rid of the STR meta entirely. The best way to go about it yourself is to tell anyone who asks about accessory choice that there are pros and cons to both, followed by what those are. Then from there the player can decide what they feel comfortable with rather than getting forced into wearing full Slaying ~or they're bad!!!~.