I don't have super strong feelings about it honestly. The ATX is a great bike if it meets your needs, but truthfully it's pretty inexpensive an not particularly high performance. Use whatever--do so reasonably often (well before the chain makes noise), wipe it down well afterwards, and wipe it down between rides even when you're not adding more lube. You'll be doing better than 95% of riders.
My personal preference is for oil based lubricants because I feel that while they may be slightly mesier, they provide better lubrication and hold up to wet and muddy conditions better. My work mostly uses Dumonde Tech lube which is fine, and I use it on some of my bikes. The claim is that it has plastic agents that bond to the metal of the chain--I can't really evaluate that claim, it works fine. On others I use Chain-L--which is thick, gross smelling, and messy, but I do think provides very good, long lasting lubrication. I don't like wax based lubes generally, and I think that TriFlow is too thin and easily washed away to be a particularly good chain lube.