Just to try to help out and shed some light on this for anyone else who is wondering, I have actually played all 5 combos in the last 2 months; M/Wd, M/d, M/s, M/w, and M/r. Here is how they stack up, in both PVE and PVP.
PVP: It is true, M/wd and M/d have the highest hitting instant cast skills, and both do great in PVP; it will come down to whether or not you want heals, so if you want to heal yourself, go M/d. Personally I prefer M/r for PVP as Cursed fangs has no cool down, so you can spam as long as you have energy. Stay away from M/s at all costs, as fire shot will get dodged all the time by rogues and warriors, and M/w lacks the insta casts of the other 3 to be effective in a quick shootout.
PVE: M/d and M/wd fall behind here, their insta cast skills do not translate well for the burst phase at all. If you had to pick between the 2 for PVE, I'd honestly choose neither and go M/w or M/s. M/w will absolutely crush both of their DPS, and will out damage a M/s in most fights as well. Having just tried M/s vs. M/w, M/w is the king of PVE dps. The only outside choice, as many people on Eu roll one, is grabbing a M/p; sounds like you are an elf however, so I'd roll M/w.
With the 3 class system, I'd recommend going M/s/d if you like to heal, as you could also run a D/s for pro heals. If all you want to do is top the DPS chart, I'd go M/w/wd or M/s/wd, then you can run all sorts of other combos, like W/wd, Wd/w, S/wd, and Wd/s. In the end, it's going to be up to you as to what you prefer.