Ivanova was never one of my favourite characters on the show, but she got better as the series went along.
Lochley, never a great fan of either. Definitely preferred Ivanova I think.
The final season in general, is very poor during the Telepath crisis thread. After that, the ISA/Centauri stuff is good, and the final 5/6 episodes are as good as anything that B5 aired.
Should also point out that Day of the Dead was superb as well.