Personally I think instrument time in the airplane is more valuable. Because of the realism of the training, and because of the huge savings that can be made vs a simulator. Obviously that last bit depends on the cost differential, but where I went the cost for the SIM was nearly as much as the airplane.
Obviously a SIM has its uses for certain training scenarios; holds repeating approaches etc but the truth is you won't use the SIM like that - you're first 10 hours maybe, but after that you'll be practicing full routes, which would be better done in the airplane.