I've got the BenQ eReading Desk Lamp which I find a bit more flexible than the screenbar style fixed to the top of the monitor. Highly recommended !
Wife has the BenQ Screenbar Plus on her iMac, similar to Halo but with a wired Controller if you'd rather not have the faff of batteries for the wireless one. Saves £30 as well.
Slight aside, but I can't believe how poor the performance of the iMac is compared to my Thinkpad T480. She won't change it though ... fully signed up to the Apple Kool-Aid LOL. I think it might be another example of Apple crippling their hardware with software updates to force you to upgrade.