Love my Dewalt...used them "professionally". Started to see a lot more Ryobi, Ridgid and Porter Cable from the new guys.
Great reviews on the Porter Cable, 50-50 on the others.
You can buy a porter cable "starter set" for hundreds cheaper than an equivalent Dewalt set. Tools, batteries and multiple chargers are also less expensive.
Just remember, once you buy the brand...you are stuck buying additional tools/attachments for that brand. As much as I love my Dewalt, each tool is roughly double the cost of a Porter Cable.
Figure which will fit the budget, the amount of use (Dewalt takes a lot of abuse)...
then get a minimum of 20 volt.
Wanted to add
Thing that aggravated me the most about Dewalt was the lack of a multiple battery charger. The others all have a relatively cheap 4-6 battery charger, but dewalt only had a charger/inverter that was ridiculously expensive.