Frontline seems not to work now, yet if you spray teh tick/flea, it still dies. It was never great for ticks though becasue it was only ever on the surface so the flea, in running around, picked up enough to die. The tick stays still so doesn't get enough. Advantix and the Bravecto/simparica products work really well, with very few side effects recorded. I'm aware of the link to epilepsy, although its not an absolute link, not least as epilepsy is poorly understood anyway.
However, many vets (self included) are moving away from regular/blanket parasite treatment due to the probability that they are part of the reason for insect decline. Ticks are a nuisance for the dogs, rahter than a major problem, so currenlty I'm picking them off!