Ooohhhh, that is a great (but tough) question.
B&M Cheshire is a great soap, dominantly bergamot. But it smells more like Earl Grey tea than citrus.
I am partial to lime. Castle Forbes is the best lime cream I have tried and Mike's has the best lime soap I have tried.
Combine the bergamot and lime and you have another favorite from Maggard's.
Mike's also has Orange, Pepper, Cedar which is very nice but not straight up citrus.
Catie’s Bubbles has sugary citrus with Boucles Fruite (aka Fruit Loops) It smells EXACTLY like the cereal. I didn't think that sounded appealing at all - until I used it. CB Purple Grapefruit is exceptional, but more lavender than grapefruit to my nostrils.
Haven't used a citrus soap from WSP or Reef Point. So, if I limit to my top 5 and extend it to citrus containing soaps, it would be:
Barrister & Mann Cheshire
Catie’s Bubbles Boucles Fruite
Mike's Lime
If I extend beyond my top 5 and just consider pure citrus:
Castle Forbes Lime
Mike's Lime
Maggard's Lime Bergamot
Honorable mentions:
Dapper Dragon Blood Orange
Mike's Orange Pepper Cedar
Muhle Sea Buckthorn (kinda citrus, scent is amazing but performance is just okay)
TOBS Grapefruit
Truefitt & Hill Lime
That answer is guaranteed to be longer and more useless than you intended when you asked, but I love too many soaps.

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