Not quite sure how you seem to think "Top five, maybe" equates to "Barely makes top five", even more baffled at how you seem to think "five" equates to me "implying there are tonnes better"?
For clarity, the original comment was not meant to mean there are five better. It was meant to question Swarm being the best themed ride in the Uk (Nemesis, imo), but it'd still be one of the best. I can kind of see how you could read it that way, but that wasn't how it was meant.
As for my second post, the rides that are there or thereabouts are Oblivion (only due to it's length meaning it doesn't require masses of themeing), the pirate waterfight thingy (Battle Galleons?) at Alton, Hex, Space Invader thingy at Blackpool.
There's your four. And again, for clarity. I'm not saying any of them are definitively better. Just that I'd have them up there behind Nemesis but way ahead of most other rides in the UK.
Edit: Rofl, and just to show my relative ignorance, I was completely oblivious to the fact Space Invader hasn't been there for a few years now.