I've had the best luck cleaning with kerosene and using a dry lube. I always try to avoid high pressure water on an o-ring chain. I reapply the dry lube every 1 to 4 rides depending on the conditions and clean with kerosene when things look built up. If I'm pressed for time and everything is wet, I'll spray it down with wd40 to prevent rust and do a more complete maintenance before the next ride. I've heard of guys using nothing but wd40 and getting good life out of a chain but I haven't tried that yet.
I don't know how much good quality lube matters in the mud/wet season because after 100 yards of riding, everything is pretty well covered in mud and grit anyway.