Even with crap solar number I was still able to work the C21 ON 2 of the upper hf bands in cw/ssb, both liberia stns on 17 ssb and ft8, san andreas on 17cw/ssb, vp6r on all bands from 10 to 40meters on cw/ssb mostly and even some ft8, gibraltor on 17 cw, the Zk3a on all bands from 12-80 mostly cw/ssb and a few ft8's (I missed the zk on 10 meters cuz of work), finally rounding off a sprinkling of 10 meter south american stns on ssb/cw most weekends.
My antennas are just Simple phased verticals for 40/30 erected one at a time for the desired band, 40 or 30meters.
For lower bands one 40 meter vertical is loaded to get on 60/80 meters.
For 20-12 I use single moxons at 24 feet which are erected on the same mast/mount depending on the desired band that I want to work and finally a long boom 4el owa at 32 feet for 10meters which is my only permanent mounted, non armstrong rotated antenna.
Whatever antenna that you can get in the air then get it in the air and try all bands that you can.
The only difference that I have observed between low SFI and high SFI years are the duration of the openings.