power or ground?

I have several lights and other electronics set up in  my car and thinking of doing some rewiring to make it simpler.  What would like to know as to which would be better. to have all the lights and everything hook directly to power and the ground wire to the switch or the other way around?  I have the switches right now on the power wire with relays on them since before I was frying switches because to much juice going through the switch.  Just looking to see what others think about this.

Six of one, half dozen of the other.  The only thing that may be a deciding factor would be if you had a switch with a built in LED, This may document where it is installed in the circuit.  Or should I say this may decide what is triggering the relay.

Ditto & ditto.

Also, ground switching is great for paralleling inputs (switches, triggers etc) without worrying about different +ve supplies nor the need for diodes (generally speaking).

But ground switching often leads to problems where "leaks" occur - as evident on old Beetles and Nissan/Datsuns (with GND switched headlights - eg, dim high beams with low beams; dim RHS low beam etc) - BUT they are GND power switched as opposed to an intermediate relay that is GND switched, and I can;t recall seeing problems with GND switched relays (except wet or water-logged relays).

The main thing is that you have relays (yay! another one that switches LOW current and minimises high-current wiring!).
And that can usually be reconfigured for either switching polarity quite easily.