Personally, I've found makita to be one of the worst. Their batteries all have a unique ID chip which communicates with the charger. If it fails to charge it more than 3 times, it permanently disables the battery. So it's not at all friendly for someone wanting to replace cells themselves.

I wouldn't trust them for contractor/professional work, but IMO ryobi has done the best job. They've never changed their connector, so a 10 year old drill that came with nicad batteries can still be used with a brand new lithium cell. This is great for a homeowner, you don't have to buy all new tools when Dewalt changes their battery design after 5 years.