I've owned the A99 and the Maco V58....
I ran them side by side. The Maco definately wins hands down. Better receive, better TX (actually has more gain than a dipole antenna, whereas A99=less than a regular dipole in some people tests I have seen)
I think it goes this way: A99= -.1dBd (dB gain vs standard dipole antenna) whereas Maco V58 = +1.5dBd gain.... I think I pretty much confirmed this comparing the 2 antennas. Never tried it against a properly setup dipole though.
If you have room for the Maco V58, as it has large radials at the bottom that stick out quite a bit, then go for it, fits your budget and is better performer than A99 for sure 100%.
If you don't have room for the radials, but are not limited in antenna height, the Imax 2000 is reported to work excellent. I ordered one, will be in this week, will test it out, I don't have the A99 or the Maco V58 anymore, but I have a M103C yagi beam antenna to test the Imax 2000 against, I tested it against the Maco V58, so I should be able to get an idea of how well it would compare to the V58 performance...
I think the Imax 2000 is a 3/4 wave over 5/8 wave design or something like that, an old trick that was used in antennas a long time ago that works very well, reportedly... I will find out soon! Other locals that went to Imax 2000 from other standard 5/8 or 1/2 wave groundplane type antennas reported to me that they were just as or more happy with the Imax 2000... only thing is it bends ALOT in the wind, but will survive for a good while.