Any recommendations concerning CRW photos?
If you mean CHDK CRW files (which are just frame buffer dumps, not in the actual Canon CRW format), my recommendation is: Don't use them.
Outside of some corner cases, there's really no reason to prefer them over DNG, and a lot of reasons not to.
I have not used CHDK for a while because my latest Canon P&S is Not supported.
Since this is the CHDK
forum (and specifically the CHDK raw sub forum), it's likely waterwingz thought you were asking about DNG viewers specifically for CHDK. You're welcome to ask here, but for non-CHDK use, you might get better advice on android / smartphone photography forums.