Take a lesson/flight in each type of aircraft. Glass cockpits are definetely the future of aviation but good ol' "steam" gauges will be around for a long time. All things being equal, choose the one that feels right for you.

I have to admit, I'm a strong proponent of glass cockpits. It's no longer just speculation...it's now a documented fact that glass cockpits in general aviation airplanes have saved lives. The electronic instruments are just more reliable than the gyros, plus theres a wealth of information available to the pilot to enhance situational awareness.

However....

Like transitioning from any aircraft to another requires some training, transitioning to a glass cockpit aircraft requires transitional training in order to use the equipment properly, safely and to it's full potential. The FITS transition programs are great for pilots who want to transition from the steam gauges to glass and these courses can typically be completed in 3 or 4 days.

I agree with airfreddy...there's just no substitute for good old fashioned stick and rudder skills and there is a tenancy for the technology to distract pilots from flying the airplane. This also underscores the need for proper training. Even in steam gauge airplanes student pilots have a tenancy to keep their eyes inside the airplane and stare at all the dials and knobs. It's a habit that has to be broken early.

I'd say glass is better, but not necessary for training.  If money is a factor, then old gauges are cheaper to learn in.  You can always tranistion to glass later at little cost and effort.  Then you will be experienced in both.  I prefer to teach primary students with the old style 6-pack.