Ski poles are often purchased as an afterthought and that's a shame. The most important thing about buying ski poles is to get the correct length. Too long and you end up flailing them around as if doing an impersonation of a windmill, too short and you are forever skiing into the bottom of them as you make your turns.
The most consistent way to get the right length is to turn them upside down and with your elbows by your sides and the top of the handle on the floor, grip immediately under the baskets. If the angle formed between your upper arm and your forearm is a right angle then that's going to be within a whisker of being spot on. Measure the distance from the floor to the pole tip and that will be the length you'll need.
Please remember, if you are racing you will probably benefit from going 5cm longer than the above test suggests (to get better leverage out of the start gate) and if you like skiing moguls a lot then you'll probably be better with 5cm shorter than the "right angle test" suggests. Freestylers often go even shorter but this is very much a personal thing.
As for grips, best to try them but if you can't, always go for the softer, rubberised grips rather than the hard PVC ones, they are much more comfortable to hold for six hours a day, will give you better feel and much more confidence in your pole plant.
Leki and Scott are our main brands but we also have poles from Fischer, Head, Line, Salomon, Apo, K2 and Rossignol.