Dick,
There are so many factors when you put antennas in an attic, it's really difficult to answer your question. In general though, anything outside is better than inside. However, an outside vertical close to your condo structure will have strange radiation patterns, plus the ability to have and arrange radials. RFI will also create problems, especially at higher power levels. From your description, the lack of much metal construction material and objects in the attic is in your favor.
Now, my experience similar to yours. I am in an antenna restricted HOA community, and have remotely-switched mono band dipoles for 10, 12, 15, 17, 20, and 40 meters in the attic (single story house), also with very little metal stuff to affect the radiation. I also have a screwdriver antenna mounted on a 6'x70' steel fence (counterpoise) about 20 feet in back of the house. As far as radiation comparisons, it depends on propagation as to how well each one works when talking to the same station and switching back and forth. Each one works better than the other at different times. The main difference is on receive. From all the electronic gadgets and appliances in the house, the attic antennas are more noisy, as much as 3 S-units more than the screwdriver. Obviously, if you can't hear them, you can't work them, so I find myself using the screwdriver more.
And then with the vertical, you have the HOA to contend with. I feel your pain

. Experiment if you can, and see what works better for you. Good luck.
73, Bob K7JQ