Ideal length of blade?
No matter what you end up buying, always wear eye protection. ALWAYS.
A friend was trimming my trees and got something in his eye. We thought it was just a sliver of wood. Five days later, he’s in extreme pain. Turns out there was a teeny tiny piece of metal in his eye and it had started to rust. I needed a magnifying glass to see it when the doc removed it. We were shocked. Never expected to hear the word “metal”. The best we could figure is, it was probably a piece from when he sharpened his tool.
I suggest going to a store and handling the tools. Consider how long you will be using it at one stretch and if it will get too heavy too soon. Make sure the handle fits comfortably in your hands so you don’t get cramps.
I like electric because I can pick it and use it. I don’t have to think in advance if I have to buy gas or charge it.
I’d get a mid range size blade. I rather cut twice than cut once and cut too much. Too small a blade and you’ll be there forever unless you’re being creative and trimming the hedges into gun shapes.
Whichever one you get spend the extra bucks and get it with the illegal alien attachment.
The illegal alien attachment will save you a lot of work and you can also use him on your lawnmower, weed eater, and they are especially good on a leaf blower.