So far I've found the following: QueryTracker Submission Grinder Publisher's Marketplace AgentQuery Duotrope QueryManager Am I missing any? Is there any difference? Which do people prefer? I don't mind paying a fee for a better service. I write historical fantasy and am based in the UK, if it makes any difference.
I mainly use Query Tracker as I like how its interface lets me check off agents that I've already considered. It also usually has links to each agents' page on Publisher's Marketplace, Manuscript Wishlist, twitter, and their own websites. Speaking of, Publisher's Marketplace is good if you become a paid member as I believe they provide information on recent agent sales so you don't have to wait for a book to get published to see it show up on an agent's bio. Outside of paid memberships, its usefulness is hit or miss as an agent's page often only has the same info that's on their website. I honestly don't have any experience with most of the other options you list, except for AgentQuery. That site was my go-to back in the day, but it looks like it hasn't been updated in many years at this point (website still has © 2015 Agent Query LLC. on the bottom). It's safe to assume any agent listings they have would be out of date and they wouldn't have any listings for newer agents.
Your list contains different services. Some will offer links to agents will others are links to publishers. Grinder is free, not familiar with all of the others, but some will make a charge. I think you would need to know what you looking for, and are your willing to pay.