Thats a tough one, both cars are very different but very good, I drive an X11 so obviously im going to be biased towards that, but its a very good, fast car!
Lewis, Yanina and all the team members are pushing very hard with the car to keep improving it, the past year the pred has become more and more popular and is starting to make a good name for itself as opposed to the preds of old (they "always" use to break)
The X11 is as bulletproof as the next car, if you read the Ebor 24 race report you will see most cars had add ons etc to help make the last, the X11 was a standard car but converted to stick pack configuration, says alot IMO..
Best thing to do would be to try both cars with good setups and see which you prefer, If your ever near southport (northwest) your more than welcome to come and try my X11, just give me a shout
I hope ive sort of helped?
Tom