I think you have to decide which program is of more use to you personally and how you will use each carrier / OW going forward - if at all. You appear to have snagged an R class fare, possibly from one of the sales, but need to decide what is next.
This is very much a personal choice but I would certainly factor in the limited use of QR miles and how you can redeem - especially as you appear to be UK based.
You may find the link below of use.
http://www.flyertalk.com/forum/qatar...Privilege+Club
I credit mine to BAEC as have been a member there since Y2K or thereabouts, so am in a different situation to you.