LEX Sucks donkey balls. Their buses are third-worldish, and their drivers are biggest losers I've ever met.
I used to ride LEX, but then I took Suburban Express because a girl I know was riding them, and I want to ride her, so I bought one of their tickets.
The difference was quite significant. The Suburban Express buses departed and arrived on time, the drivers knew how to get where they were going, the bus was nice and clean, and the drivers never farted - not once. It was like bizarro LEX - exactly the opposite.
Anyhow, based on my experiences, I'd have to say that Suburban Express is really good, and that LEX sucks.