Depends on how far you think they make it. If you think the group winners are the final 4, then it's absolutely worth it. If you think someone in round 1 can make a deep run, then yeah, it's worth picking them instead. Just remember that any eliminated players get -3 for each remaining round and no padding.
The best plan in knockout finals is almost always to pick the teams who you think will be in the final and have 4 players from those teams, plus the 5th from one of the other teams in the semis. Otherwise you have to find players who will score so many points in an early loss that it will more than make up for the other points they will lose later, and that is *very* rare.