It's only a matter of time before I get a cordless power tool.  If I get one, it will be inevitable that I will get more.  I don't like having a lot of extra chargers taking up space complicating things so I'm going to be buying into system.
Does any one out there have a opinion on what system is the best and why? 

It's only a matter of time before I get a cordless power tool.  If I get one, it will be inevitable that I will get more.  I don't like having a lot of extra chargers taking up space complicating things so I'm going to be buying into system.
Does any one out there have a opinion on what system is the best and why?

It depends on how much you intend to use the tools.  Considering you don't already have one I'm guessing you won't need heavy duty, pro-rated tools (which are usually 18V). 

I'm very happy with my Milwaukee 12V cordless tools.  I suggest you get the "Fuel" versions where you can, as they have the more efficient brushless motors, also get some 4.0 or 6.0Ah batteries if you want maximum grunt (eg 1/2 drive impact driver is very impressive).  The smaller batteries are lighter and more compact, but they can't supply the current & runtime the bigger batteries can.  I've read some bad reviews on the non-genuine batteries, so even though they are much cheaper I've stuck with the genuine ones. 

I've very happy with my Milwaukee 18v Fuel drill and impact driver.  Though I'm also very happy with my Rigid tools which cost less, and have a lifetime warranty.

Thank you both for replying. 
I am between jobs right now.  When I go back to work I will be using tools daily to earn a living.  So pro rated is very likely what I will get.  A lifetime warranty is all well and good, until you discover you have a lifetime supply of cheap tools.  I want something I can count on because when a tool fails time is lost and that's money.  I have been getting buy using corded and air tools so far.  I only have one cordless tool that will eventually fail, it's replacement will be part of the integrated system.

There are many brands out there, and I have just tried a few. And even within those few there are quality differences - the drills might be great, but the grinder not so much and so on. Personally I settled on Bosch blue series. Most have survived admirably, and the system got a wide variety of tools, so I've stuck with them. (Bosch blue stationary tools have some mixed feedback though which is also my experience - as opposed to their hand held power tools which are generally very good).

Not some ultimate answer, just my choice and experience.

Edit: The why I landed at that: At some work I had long ago they bought all kinds of stuff from all kinds of brands. No real plan or anything they just bought the closest thing at hand as the need came up or some old tool failed. And this was a hostile wet, salty and dirty environment for tools so a lot of them did die - in fact they had a separate bin just for power tools. After I while I noticed that most of the tools still in circulation were blue, and that there were few of them in the bin. The blue ones were blue Bosch and Makita. Of those, since I liked a few of the Bosch ones, it was Bosch for me later.

I bought into the milwaukee system a while back, and have few complaints over the years.  And I learned the hard way to stick with OEM batteries!
That said, my second choice was bosch.  You can find people with good and bad feelings for all the colors, but I wouldn't hesitate to recommend either of the above.

After years of frustration with DeWilt, I changed to Bosch Professional, pick a voltage and away you go. The plus point is that even with the oldest tool I could still get replacement batteries for it.

I highly recommend ryobi 18 volt one+ , i have many tools and 13 batteries and have had no problem with medium use. Im a plumber on the weekends and the tools have worked very well for me i have a drain auger, drill, sawzall, multiple lights and air pumps and my favorite is my 3 gallon wet dry vac, but honestly it really depends on what your using them for, pro use, around the house, what have you. but as far as number of available tools go im pretty sure they have the biggest selection, however i may be wrong

There's as many opinions on power tools as there are brands that make them.

https://fein.com/en_au/ is as good an option as any, if for some reason you want to go German.

In practice I can't actually detect any difference between American, Japanese or German power tools. All the quality brands are fine.

I've never used Festool, they seem to have their own section of the store, with a red velvet rope and a serious looking fellow with dark sunnies keeping an eye on them. For the price tags on them, I assume they measure, do the job, clean themselves, take the dog for a walk, and order tea as well.