I have long acquaintance with the Spendor line and can assure you that 3/5 is a fantastic speaker. However, as I don't know the other two models, I cannot offer more meaningful comparative feedback.
Given your tastes and budget, I am not sure why you are looking for a mini-monitor. Is the space for this system extremely limited? You can probably find more satisfying alternatives (with respect to bass at least) among floorstanders.
Given your tastes and budget, I am not sure why you are looking for a mini-monitor. Is the space for this system extremely limited? You can probably find more satisfying alternatives (with respect to bass at least) among floorstanders.