What are the best blades for mowing with this mower?
I have an la120 which I think is the same as yours, but a year older. It's a hydro with a 42 inch Edge deck.
I have three types of blades for my mower and all John Deere.
3 in 1, the blade that came with it, is a combo blade that will mulch, bag and cut.
Mulch blade, which is made for mulching
High lift blade, which is made for bagging.
For just plane mowing, I found the 3 in 1 blade to be the best, I had some striping issues with the mulching blades, and really did not see much difference in cutting the pieces smaller. The high lift blade is a blessing for the fall and spring. As it almost eliminated my shoot clogs. I went three years without it, and I could kick myself for not switching sooner.
So if you just want to mow, I would suggest the 3 in one Deere blade.
Others might have a different opinion.