I don’t think there is a "best technique" but I tend to block things off a lot, it makes it feel like a different map.
I would like to add an option: "none of the above." I find all of those excessively overused (except perhaps blocking off areas, and, in some rare cases, teleporters. I think that original ideas are far more important.
LOL... I was just thinking that Lance... I would say none of those makes maps more enjoyable... I would say... balance, originality, effort, etc...
I like original maps, not really the balanced type, so I love blocked off areas in a specific point of a map.
Being able to block off areas (and more important, keeping them blocked) is very important. Also floating platforms come in handy too. And as AZN said balance is very important on a map so never, NEVER forget it.