french press vs. chemex - oil absorbed by chemex filters?

The Chemex process does absorb oils, and also reduces the total time the coffee grounds stay in direct contact with hot water. But the issue is less about better-vs-worse, and more about your preferences wrt the characteristics of how you like to drink your coffee.

French Press yields, assuming all else is the same, an earthier, more viscous brew with more pronounced bitter notes that many people prefer. This is related to the presence of oils and suspended microparticles, much of which the Chemex filter removes.

Assuming the same grounds-to-water ratio and the same bean, a Chemex process will yield a coffee infusion with relatively sharper high notes, enhanced acidity and lowered bitterness. For coffee varietals and roasts that have more delicate, perfumey elements, Chemex can be a preferred method. Many coffeeshops prize these more floral, wine-like elements in their coffees and want their customers to experience them.

Besides choosing to showcase the more delicate elements of the coffee beans, many high-end coffee houses also have logistical concerns facing them as they work to assure the same coffee experience cup after cup. Assuming the patron receives a ready-to-drink (or ready-to-lighten/sweeten) cup of coffee, Chemex offers a process that is easier to measure, time, brew and dispose/clean up than French Press when presented with a stream of customers. While, French Press is easier than Chemex if you give the press to the customer to press and pour when they wish, that means the coffeeshop cannot control the final brew quality, which is often what they prize. Assuming the French Press is poured into a carafe, this problem can be ameliorated, but dumping, rinsing the pot, then unscrewing, rinsing and rescrewing the press is more challenging under time pressure than simply lifting out the Chemex filter and discarding.

Personally, I prefer French Press. I like the heavier, more viscous brew that the process yields, and I lean towards Half-City or medium roasts, which are lower in bitterness in the first place.

Here's a good example of a method very similar to what I do: http://stumptowncoffee.com/brew-guides/press-pot/

Ultimately it's about preference in taste and preference in process. Some people will prefer French Press while others swear by Chemex.

The Chemex brew method can absorb oils, mainly with paper filters. Reusable filters tend to allow more oils through for a bolder taste. There's also a further level of control with this brewing method. Your pouring technique, how you bloom the grind etc. all gets taken into consideration with the final brew.

The French Press brew method mainly leaves you with a fuller cup of coffee when compared to the Chemex. It can be richer, again taking into consideration the type of coffee you're using, grind size, and the effort you put into the press itself.

SweetHome.com recommends pourovers and claims that

Unlike a press pot, it uses a paper filter, so you get more flavor clarity (at the expense of less body, admittedly, but flavor clarity is probably what you want if you’re spending good money on good beans).

They have specific recommendations for both manual and automatic pourovers, coffee grinders, scales and even a kettle.

They also point to an index of instructions of various brewing methods.

I prefer Chemex because that last sip doesn't have any particles in it. The press guarantees a mouthful of coffee sand if you want to finish your cup.