I've used both Off-Ice and Roll Line Lineas and of the two, the Lineas are by far the best in quality and value. If you go with Off-Ice, then you have to use their own brand of wheels and toe stops and the toe stops wear out very quickly if you're spinning. Roll Line work with many different brands, sizes and hardness/materials when it comes to wheels, and have two different sized toe stops to cater for different skating styles. This makes them much more flexible for use on different surfaces and for different preferences. You can also adjust the rocker on them to your personal preference, which is fabulous.
The main difference, however, for most people is that Off-Ice have 4 small wheels and Linea have 3 larger ones. The Lineas are far faster for far less effort! But - and this can be a big but for some - the Lineas are considerably shorter at the back, whereas the Off-Ice have pretty much a whole wheel sticking out behind the heel of the boot. As an ice dancer, I much prefer the Lineas for this reason and felt that the Off-Ice were clunky. Your mileage may vary. I suspect that Off-Ice are much easier to get used to for the average/lower level skater but I was very happy when I swapped to Lineas as the speed, manoeuvrability and lack of "heel" suited me much better.
There are several Facebook groups which are great fountains of knowledge on the subject of artistic inline skating, including one called Pic That Skate.
And as transmissionoftheflame has pointed out, surface is everything.
