YMMV, but...
both are great playing guitars IMO, and incredibly hard to beat for the money.
keep in mind:
- they sound diff - Charvel pups tend to be more consistent. WG pups can/use to be hit or miss (dark to me). some pups were great and others were yuk. i think for a lot of guys, a pup swap is imminent with both of these. if you think you may want to go that route, keep in mind not every pup will fit in the WG w/o some rounding of the legs. also, the FR on the WG is slightly recessed, and the SD is fully recessed. to me that was a big deal. i'm just not a huge fan of the fully recessed trems.
- they play diff - the scale is the same, but to me, the WG feels/plays like a shorter guitar, especially once you get past 12. i actually prefer the WG in this regard. the neck shapes are also diff, IIRC. Charvel more flat and wide, WG smaller and tighter radius.
- they hang diff - see above about playing diff. same applies here
- a curve ball would be try the EVH 5150 series. same "s" shape body as the SD, i guess there are some slight diff. you get the HH pup confi with a 3-way toggle in the lower horn. they, imo are more closely comparable to how a Charvel SD plays, only with the EVH pickups
definitely try to play before purchase, or have a solid return policy in your hip pocket.