Redhat, whatever version was around in the summer of 1997 when I left university, I missed Solaris big time.
I had Redhat on a machine with a dual boot with Windows NT. NT would give me the blue screen of death on a semi-regular basis. A year or so later the machine got a hard disk reformat, a clean Redhat install and became a dedicated database server - during the next 2 years it was on the whole time, rebooted only on a dozen or so occasions, and never ever crashed despite its low power (it had no desktop installed) and our throwing rather a lot of database activity at it.