Originally Posted by Demise

VAWA:
Leads directly to permanent residency
Either not subject to any quota (if abuser was a USC) or charged into F2A which is current (if the abuser was an LPR)
Can (generally) concurrently file for AOS (and get EAD/AP that way)
Will get a C31 EAD upon approval
Can naturalize after 3 years (if abuser was a USC spouse/parent)
Abuser has to be a USC/LPR Spouse or Parent or USC Child
No legal requirement to report the abuse to authorities or partake in criminal proceedings
Overcomes an EWI
Can overcome a 10 year and permanent bar if you can demonstrate a connection between abuse and overstay/illegal entry/illegal re-entry.
Children under 21 can tag along with you (except cases of abuse by USC child)
Have to file within 2 years of death or divorce (don't have to be divorced first to file)

U-visa:
Leads to U visa status
Subject to 10,000 quota per year for principals only (derivatives are not subject to a quota)
About 4 year waiting time for approval (though you will get deferred action and an EAD sooner)
Can/has to adjust status after 3 years
Can naturalize after 5 years
Abuser or perpetrator can be anyone
You have to report the crime to authorities and partake in the criminal investigation and the relevant law enforcement department has to sign off on I-918 supplement A
Overcomes basically every single ground of inadmissibility short of the absolute kiss of death ones (e.g. partaking in genocide, being a nazi back during WW2, and few others, can overcome a permanent bar or false claim of citizenship even)
Spouse (U-2) and children (U-3) under 21 can tag along. If you are under 21 at time of filing parents (U-4) and siblings under 18 (U-5) can also tag along.
No time limit for filing