Well it depends, actually there are servers for almost every region , since european guys have United Kindgdom , south american guys have servers located in Brazil and North American have also servers locate in the EEUU. So I think now there is no reason for use proxies, maybe if you want to low your ping some ms but it wont be that much unless you play from Russia or Egypt , maybe those countries need a Proxy to play better.
And they are safe? I will say yes because there is no need for a proxy company to steal or to do ilegal things which can make their bussiness go down so quickly , so I think they are all reliable.