Here are some answers:
John4865: "KnowBe4 is an incredible value. So much so that I have not bothered to shop the competition."
SQLRage: "I can't speak for the competitors but KnowBe4 is very cheap for the impact that it has had on our company."
Rickmarvel: "KnowBe4 is a good option as user education is the key to defending against phishing attacks."
Harpy: "I personally use KnowBe4 now as I feel its easier to use, very good product and can highly recommend it. Before that point, we were using Wombat.
Dimforest: "Honestly... just save yourself the time and money and go with KnowBe4. It's the industry standard for a reason."
Denise5318: "Getting KnowBe4 was some of the best money I've spent here at the library."
Here is the whole thread (and poll with votes for platforms) on Spiceworks:
https://community.spiceworks.com/topic/2183603-phishing-campaigns?page=1#entry-8142388
PS, If you want to see KnowBe4 compared to other products in an objective, legit platform that makes sure the reviews are fully vetted, check Gartner Peer Insights: https://www.gartner.com/reviews/market/security-awareness-computer-based-training