there are adv/disadv to both
I would say the electrical are generally more expensive and of higher quality and therefore maybe a bit more accurate.
but a totally accurate gauge may not be needed , the sweeping action can tell you almost as much if not more....
I dont like digital gauges but you might.
depends on the gauge type too (boost , exhaust gas temp , voltage) all have very different wiring needs.
direct line tends to be easier in some cases (boost gauge) , but then you run a long tube to the dash which if punctures gives you a boost leak...
lighting style and colour are also considerations
you may also wish to consider a combined 'gadget' that may use the OBD port for the values you want if you want it all ?