I've not convinced that slug traps do much more than make you feel you're getting revenge on the little blighters. Getting some sort of balance and creating the right environment for slug predators would be the optimum solution. Amphibians such as frogs and toads are one group that are supposed to eat them, as are ground beetles. One thing I wonder whether would work is sunken beds around vulnerable crops, so that beetles fall in and are less able to get out, sort of like reverse raised beds with edges. I have to say I haven't tried it yet though.
When I first came here I had a lot of trouble with slugs, almost everything I sowed was eaten. The things I found helped was transplanting strong little plants, rather than sowing direct. Tasty plants such as cucubits can be protected with a little collar in the form of a cut down plant pot. Here is a picture of some results of my trial of defences using lupins as a sacrificial bait.
The full test is here
. You can see the eggshells were not effective at all in the long term for me despite a really thick layer, but a barrier, even without copper tape was reasonably effective.
These days I seem to have a better balance with the slugs, although that might be because I sow far fewer seeds outside these days, and slugs are less of a problem in the drier polytunnel. It would be interesting to repeat the lupin experiment now though....
As far as plants that slugs dislike as opposed to ones they like, their tastes unfortunately coincide with ours. I don't think they like tomatoes, or most herbs. I wonder whether my interest in perennial vegetables was partly inspired by trying to get a headstart on the slugs - since the plants are bigger, or grow away faster, the slugs seem to affect them less than poor little seedlings