some considerations
 

Cordless is great, got lots, every day it seems there are new types of tools coming out cordless.
My recommendation is to first consider what tools are available from "The Manufacturer", because it seems that the batteries are all different, (not interchangeable), so, you are locked in to their brand, unless you want to have a lot of chargers and batteries laying about.

The second consideration is basically cost / durability. This runs the gamut from Harbor Fright to pro grade stuff like milwaukie.

In construction, flexibility and durability rule. I went with Milwaukie, because i used it every day and on the weekends. All those tough construction tools seem to get used on the cars too, particularly the 12 volt and the 18 volt impacts.

Good friend of mine swears by the Harbor Fright stuff like Bauer.

ciao

Hand powered stuff - Milwaukee has the most options off of 1 battery style. But you can opt for a larger / higher amp discharge battery for additional cost, that really sets them apart.

Aa far as lawn stuff, I have older Black&Decker weedeater / leaf blower / tree trimmer that all share the same battery. They are low priced, durable as I really overwork them. I've replaced the weedeater once, it didn't owe me anything.

Depending on your yard acreage, you might want something like Stihl battery power stuff