On GTs, I prefer the classic look with them on. It really depends on others. If you have a killer top, it might look cool off. I guess I just prefer the classic completed look of the pickguard on the guitar.
I prefer it on myself. I do like it off on some Customs but on more time than not.
I thought for sure I'd rip off the gold covers and pickguard off of the 57 RI I recently picked up but I'm liking the look as is right now. I still may do it but on the fence.
What the heck are they guarding anyway? If they're meant to guard the finish so that it looks better...well, you can't really see the finish anyway because the darn pickguard is... um...guarding it.