I find it very strange that I am supporting QXP 8 after many years spent trying to convert hardened QXP users to inDesign. Up until CS2, inDesign deservedly held sway on OSX. Then QXP7 and CS3 came out and started to match each other feature for feature.

inDesign CS4 is… problematic… and expensive to upgrade to. Adobe seem to have developed Quark-of-old's style of customer support whereas Quark have seen the light and realise they actually need customers. QXP 8 is what version 7 should have been (and version 7 is what 6 should have been). Quark lost sight of the ball and needed to get back into the game in a hurry.

As far as the interface is concerned, it is always a matter of personal taste although Adobe have consistently used one box to achieve one end result throughout their product range whereas Quark prefer multi-tabbed boxes which will serve a multitude of settings. Adobe have vertical tabs down the side of the screen while Quark use horizontal. QXP 8 has a (IMHO) more developed and user-definable tool bar and contextual measurements pallet while inDesign has a far better help system.

For speed, try them both. I find QXP 8 quicker to set-up and lay-out a piece of work (especially books) and what I read on the web would agree with me. (Please don't ask for references, it is Xmas holiday after all).

For the future, I see Quark possibly being side-lined and undeservedly so because it is as good, if not better than inDesign. Just as Freehand did with Illustrator and @£$%^ (fill in blank) was usurped by Photoshop. Younger designers might know only the program they use rather than having a more open and experienced view about things. We started in Calamus before moving to Pagemaker. The former has been reborn while the latter is a page in Wikipedia. Nevertheless, Calamus is unlikely to challenge for the DTP crown.