The Samsung because Sony's CS and warrantee sucks! They wanted to fix and not replace a brand new G420. I told them to stuff it and returned it to the place I bought it from.
Truthfully, if the specs are similar, the monitors should be very similiar if you get a good one. One that isn't damaged in shipping or one that hasn't passed by the poor QC dept. When I started monitor shopping 2 months ago, I was shocked at the poor QC of monitors these days. You can stand two identical monitors side by side and see differences. It's that bad.
My advice if you're not worried about price is buy locally and see the exact monitor that you're going to be living with before you take it home. If not, buy from a place that has an excellent return exchange policy. Don't trust Sony. If you have problems the 2nd day you have a Sony, they will want you to take it to a repair facility and wait 6 weeks for it. I'm not sure what Samsung is, but I think they have an exchange policy. I'd check.
Sal