Here's an example: A 40m monoband Yagi, three elements, on an 80' tower, clear of all obstacles, with a rotor. Better yet, a couple of properly-phased, stacked Yagis, up a bit higher. That's the most effective QRP I've heard of anyone using. I posted elsewhere about my club's Field Day station putting up a 40m beam on a large tower, and how well that worked with a half-watt Rockmite the night before Field Day (but for the actual FD event, they switched to a QRO radio). The problem with such a strategy is that, though it works well with low power, it doesn't integrate well with the spirit of QRP. That is, it's not small, lightweight, nor inexpensive. It's not portable, unless you purchase a trailer for it and consider "towable with a full-sized pickup truck" to be the equivalent of "portable". If you take cost and portability into account, you must compromise on performance, and the "best" answer depends on how you define your constraints, and what you want to optimize for. Full-sized resonant wire dipoles are a common good strategy, but you've got to support them somehow. Trees might work, but they're often too low for the lower bands, and they're not available at every operating position you might want to go to. Portable masts are always a compromise between height, strength, ease of setup, bulkiness of transport, and cost. If you're interested in some of the strategies and compromises of portable QRP antennas, a very good read is NE1RD's "Buddipole in the field" http://lib.store.yahoo.net/lib/buddipole/BIF2.pdf http://www.bsandersen.com/Rsc/Rsc/buddipoleInTheField.html That goes through some of the strategies that can be used for constructing portable antennas with the Buddipole system. And it reinforces a point I've made several times, that the Buddipole isn't an antenna, it's an "antenna construction kit", which allows the construction of a whole lot of different styles of antennas, of which some work well, and others don't. But the point which that book makes relevant to this thread is that there is no "best" answer. Even if you limit yourself only to the Buddipole system, that book took a bit more than 150 pages to describe the "best" configurations for various circumstances. If you add in the huge number of good alternatives that don't involve anything like a Buddipole type system, (wire EFHW, wire dipoles using trees for supports, magnetic loops, etc.) it soon gets even more involved. After all that, I say a basic standard starting point for comparison would be a full-sized horizontal dipole, tuned for the band you're using, a quarter wavelength on each side, half wavelength in total, fed at the center, up at least a half wavelength in clear air.