What’s the best antenna to have for contesting? Well, in my book, it’s the one you currently have because if you don’t have an antenna, you can’t contest!
I admire those that can put up killer antenna farms to work the world, but the vast majority of hams can’t do that for all sorts of reasons.
But different antennas will do better in different contests than others and we should try and focus our efforts based upon the strengths of your antenna.
For example, it may be that you have a love affair with 160-meters and have that single antenna on your property. If it’s a killer 160-meter antenna with great beverages, I’d suggest operating every 160-meter contest and single band 160 on multi-band contests. Your antenna will put you in the best position to do well in the contest.
For a long time, all I had was a multi-band vertical for contesting. When deciding to be in a contest, I focused first on domestic contests. The reason for this was that a vertical would most often lose out to a beam in a DX contest, but a beam was not as effective in a domestic contest. This is because beams, if at the right height, only hear well in one direction and domestic contests require you to hear in many directions at once.
The other aspect of a multi-band vertical is that they tend to do very well on one band compared to other bands.
For example, one of the verticals I had was 33-feet high; a perfect height for operating 40-meters as a half-wave vertical with no power losses from matching systems. Forty meters was also a good band in relation to beams as not many hams have 40-meter beams.
So in a DX contest, I’d try and operate 40-meters as much as possible because my antenna worked as well as most others in the contest.
One of the things you should look at in deciding which contests and which bands to work is the type of antenna you have at your location. Each antenna type and installation has strengths and you should try and maximize that strength in a contest.