I think the best way is reduce speed
From my viewpoint, the different type will cause the same result, which is the same time to start approach. That's means it does not matter what kind of method you let the aircraft do, and they will cast the same time in the air.
So, the time is same, but let the aircraft reduce speed they will not consume lot of fuel when decent, because their could get energy from the gravity.
For the holding pattern, just one round will cast 2mins at low altitude will cast a lot of fuel for the moden fan turbine engine aircraft, especially some aircraft has just lower their flap at 10 degress or more.
And compare with the path of the two type, holding pattern will cast at least four more turns. For the moden jet, their turning diameter are very large and when turning polit will increase throttle to maintain the altitude.
The conclusion is:if possible, do not let aircraft join holding pattern.
And why we use holding pattern?
Think about the first way, it will cast lot more time to get thought FL, and a greater speed for approach. That will cause inconvenience for ATCs, especially in busy area.