I like both, but I definitely like the weight work better in RWH and there are alot of the XTrain dvds that I never reach for due to the high impact. If you aren't set on geting a "series" I say take a poll of favorites from both series and put together your own "series" taking the best from both.
My most used from XTrain: Supercuts, Cardio Leg Blast, Low Impact HiiT, Burn Sets
My most used from RWH: the 2 upper body workouts (love these), the Leg workout and the upper body circuit workout. I use the Low Impact HiiT but actually since I got ICE I used the lower impact from that set more often now.
From Xtrain I don't care for Hard Strikes, the two upper body workouts to me aren't as good as those in RWH, Tabatacise is so hard for me I rarely do it and the Leg workout is too long. I sometimes will do the premixes on the Leg dvd but for some reason it's just not one I reach for even though I thought I would.
My RWH/XTrain "fusion" series would be...
RWH Ch/Sh/Tri's
RWH Ba/Bi/Sh
XTrain Cardio Leg Blast
RWH Legs
Xtrain Supercuts or RWH Upper Body Circuit
ICE Rock 'em Sock 'em Kickbox (I know it's ICE but it's my new fav kickbox workout!)
XTrain Low Impact HiiT