OXY and XOM looks good(low debt, profitable), but they also pretty expensive to me. BP looks good as well, but cheaper, they have some Rosneft exposure and there is the unclear Macondo thing(though they did already put a lot of cash aside and it will take a while in the court), but it looks like the cheapest oil company that will do well if the oil remains low for a while.
NOV looks like a great company, well run, low debt, market leader, if the price will go down another 20% (to 50s) I think it's a good investment.
It's interesting to hear your opinion on CVX vs XOM. Both look like very well managed with very low debt, however CVX is much cheaper and I don't see why(CVX have much less reserves, but it should matter only on a very long time horizon).
I'm also looking at SLB, TESO, FI, PSX, DRQ, COP, HAL, UPL, CHK. Also offshore drillers may be interesting, they have low oil prices + rig oversupply, so they will suffer a lot for a couple of years.
I think it may be a very good opportunity to invest, as oil must go up to around 85-90 at least, they only question is when.. :)