I dont own either... I have a Humminbird Helix on my kayak
From what I have read on the kayak pages online, you want the Garmin plus, either 4 or the 5inch would be better.
A mate of mine has the Garmin plus on his kayak, comes with 300w transducer, whereas the Lowrance has a 200w transducer... have met a few who have had horror stories with the Lowrance hooks
Also, hook2 series has had a known issue with... cant remember exactly, something to do with water ingress & infeed power lead probs
Depending on your budget & if you want to keep up with new technology that is out now, try & consider getting the latest fishfinder... you wont be upgrading for years, so its money well spent now & futureproofing your gadget for the years to come
The new Gamin striker Vivids have fantastic specs on the 4inch & even better again on the 5inch (500w transducer)