In all honesty, I can't really tell much of a difference between the taste of the food when smoked with different woods. The smell of the smoke from different woods was noticeably different when I did the smoking course and we went round smoke sniffing.
But the taste of the different smokes in food doesn't really shout out because of the brining or marinades, apart from hickory, which I use for the American style smoky BBQ, and the whisky oak which I sometimes use for the smoked salmon or oily fish.
Beech dust is the easiest to use and get a steady burn without going out.
Also a tip for getting the best out of the ProQ smoker which you have is to wash it out after you finish a smoke, using a toothbrush to push into the mesh to get out all the bits of burned wood dust. Then dry it thoroughly and keep it somewhere dry.
I put mine in a warm oven to dry completely, and before I start a smoke I put in a warm oven again to make sure there is no dampness. 180 C for 5- 10 mins.
Also make sure the wood dust is really dry put the dust on a baking tray for at the same temp for about 5-10 minutes keeping an eye on the dust to make sure you don't leave it too long and set it on fire in the oven.
The reason I do this is I had a problem keeping the dust smoking after I had used the smoker for a few times and the guy at Macs BBQ suggested that I do this. Since I have, I have no problems and I can leave the smoker going over night for a 12 hour smoke with no worries about it going out.
I am not sure if I can advertise where I get my wood dust from on this site, but if you PM me I will tell you the place I use where the wood dust is good quality and a very reasonable price.