I, too am trying to decide between these products. Have you made a decision yet?

-Neil

Either product is fine I'm sure, with Velux being quite a bit cheaper $ wise. I just installed (2) Solatubes, (10") last week, and am very happy with the quality of the components, and the performance so far, even though I have yet to see them work on a clear sunny day since it's rained ever since install. I chose Solatube over Velux due to longer track record making these, patented features that give them a slight edge, they were available in stock at my dealer, and I knew I could get the tube to where it had to go. This last statement should be your first consideration. Do not buy anything till you've clearly researched your framing situation. You may need to get one product over the other for that reason alone. Velux's rigid tubing would not have worked with my offset beam situation unless I went to a 14" flexible style tubing they offer. I did not want flexible, nor a 14" light in a small room. Solatube has knuckles (moveable elbows) on the top/bottom tubes to offset the angle to get around things easier and allowed me to angle my way into a room to the left of the roof opening that had a 4" beam offset to boot. I did not see anything on the Velux site's install/spec sheets that would have made this possible with their 10" rigid product.

Install Note: I can recommend not final taping "anything" till you've put the whole run together, and to do that easier..."bolt" the lower tube to your ceiling with nuts/washers (do not use the provided "screws" that will fail the drywall in minutes by the weight of the tubing alone during setup. Use pieces of painters tape to fashion the tubes and do a complete mockup, then pencil mark the joints and positions of everything so you know where everything did align when you disassemble for final finished foil taping/screwing.
SolaTube has Raybender "Fresnel" feature on the dome to bend light down the tube, and a south faced (user positioned) deflector to do the same. My wife points out that to her...the light appears blue weighted a bit, which is probably true, due to the UV being removed to prevent fading of interiors. I'm sure a new "needed" room color could return the missing spectrum. Oh...on that note, remember that the light you get from these is very intense. It will highlight any room flaws quite visibly (wife home when sun came out once).

Correction on last post...the Velux "did" show elbows with their product, but you had to use a lay down style flashing vs. upright boot depending on your roof pitch angle. That's what it was (senior moment). Solatube pitched flashing works with most any roof angle. I wanted better snow protection, and the upright boot looked best for that.