The Sun Joe MJ104E has more than 1250 five-star reviews on Amazon. Buyer Jim has had his Mow Joe for more than a year and left it in the weather and abused it otherwise. He is happy with how it has performed. He cautions against buying the 16-gauge extension cord recommended by Amazon. Instead choose 12 gauge for 100 feet or more and 14 gauge for under 100 feet.
EGO has two 21-inch deck 56-volt lithium-ion cordless battery mowers that are quite popular and share a number of similarities: the LM2101 and the LM2102SP. The major differences between the two are that the LM2102SP is self-propelled has a larger-capacity 7.5Ah battery and it costs $100 more. For the purposes of this review we are going to focus on the features they share in common.
More than 2100 buyers on Home Depots site recommend the Toro Recycler 20333. The most helpful reviewer found the powerful engine did an excellent job of chopping through foot-high grass and the rear wheel drive gave him power while turning. He also mentioned that he could almost jog with it. Another buyer notes that his Toro still runs well after three years of questionable maintenance. He does note a couple negatives: It is a bit louder than the Honda and if you go to fast the mulch is not fine enough.