I have a question about Humvees vs Helicopters
Yes, if you have the money (and can deal with he hassle) to have several strike teams spread across bases around the globe, then the helicopter is clearly the better choice. That is also what I have done.
Another thing to note: The humvee is considered a military vessel and the chopper a civilian one. That gives the chopper another advantage: It can partake in covert missions like ski and beach resorts. However, for some reason, it cannot do all covert missions. For example, if I remember correctly, for Osrion Stakeout you still need to keep around a car or van (or land rover, once that becomes available).