I voted for Atlas. If it's about running, Kato is still the best. But overall I like Atlas most, even their parts dept. (online shopping) is the best and has not Katos high price level. My "roster" comprises units made by Atlas, Bachmann Spectrum, Brawa, Proto 1k/2k, Piko, Lima, Walthers, BLI, Kato, Lilliput(Bachmann), Maerklin and of course Athearn, including RDC with the "notorious" rubber band drive.
And, Fluesheet is right about Trix (Maerklin), great stuff and great price. Took my BLI GG1 to my LHS to compare it with Trix's GG1. They're close, but Trix's GG1 looks better. But even over here in Europe, you can buy two BLI GG1 for the price of one Trix GG1.
Tobias
PS: I appologize for any mistakes, english is not my mother tongue.