When you apply as a group, you essentially have one name in the hat. If the group name is drawn, everyone in that group gets a tag (with very rare exceptions). When you apply individually, each individual's name goes into the hat. If you have a group of four individuals, the odds of at least one of the four hunters drawing is obviously better than the group being drawn, since there are four chances versus one.
What it boils down to is whether the members of your party are willing to consider getting drawn when others in the party are not. If it's "all or none" then apply as a party. My hunter partners and I typically apply individually, since that way at least one of us hopefully gets a chance to hunt, and the others go along to help.
The odds of being drawn at the limit of a quota of several hundred tags is extremely rare, and should not be a big consideration.