Tough call, but I think I'd go with Bryant. The Raiders have trouble stopping the run, so it's questionable how many opportunities Moss will have. In addition, we don't know if Cassel will pull a Favre-like 'this one's for you, dad' against Oakland, or be a bit unfocused. More upside but more risk with Moss.
On the other hand Garcia has missed practice with a calf injury, and he depends on scrambling to buy time before throwing the ball. If it looks like Tampa Bay is going to start McCown, then I'd go with Moss.