The LawnMaster is the better machine - no doubt about it:
Superior build quality
More power and cutting options
Generally more robust and likely to last longer
Worth the £149 if both were similarly priced
But that £84 Hyundai deal is just too good to ignore:
£65 saving is substantial
Will still do the job perfectly well for years
Hard to justify paying nearly double for incremental improvements
Even if it only lasts 70-80% as long, you're still ahead financially
Bottom line: The LawnMaster is the better mower, but the Hyundai at £84 is the smarter purchase. Sometimes a great deal on a "good enough" product beats paying full price for "excellent."
You're getting solid lawn cutting performance either way - the Hyundai just represents exceptional value at that discounted price. Your lawn won't know the difference, but your wallet certainly will!
Go with the Hyundai deal while it lasts. You can always upgrade in a few years if needed and still come out ahead financially.