Well, probably the most important things you can consider are the following:
Intended OCI length (are you AR about OCIs, or can you fight off the urge to change often?)
Warranty considerations (are you bound by OEM criteria for coverage?)
Price point of products (more $ can, but does not always, mean "better")
Availability of products (do you need it NOW, or are you willing to have it shipped?)
In general, in most nearly all diesel applications, there is a multitude of success with "dino" products such as the big three (Delo, Delvac, Rotella). Note that these are just brand name product lines; you must be specific in what product you're referring to. For example, all three have both "dino" and "synthetic" oil within those lines. Even the "synthetics" are of different base groups.
"Synthetics" in their many forms offer greater ability to extend the OCI; some significantly. Amsoil for one now offers some of their products that have warranty guarantees for 3x the OEM OCI! That's pretty significant. It is not uncommon for the Dmax engines to go 10k miles with good UOAs on regular dino oil, and using the OLM. So conceivably, you could run the Amsoil for 30k? I'm not sure I'd do that, and certainly the practice would necessitate UOAs along the way, but my point is that there are possibilities for greatly extended OCIs, thereby becoming a fiscal savings tool.
"Synthetics" also give some great advantage in extreme temperature environments. But I caution you to fully understand what "extreme" means. I mean E-X-T-R-E-M-E cold (below -30 degF). Or, like Africa-desert-hot just before boiling over the coolant due to a failed water pump. Short of those examples, synthetics don't hold much advantage over conventional lubes.
OTOH, if you're anal-retentive about changing oil every 5k miles, regardless of what's in the crankcase, then conventional "dino" HDEO oil will do extremely well. There is no logic whatsoever to buying a premium PAO oil for $28/gallon, and then dumping it at 5k or 7k miles. You can go out and find some really good dino oils on sale and run them for that type mileage. For example, it's been very easy over the last sevearl months to find Delvac 1300 for $7/gallon with the rebate. Wally World just had Tection Extra (Castrol dino HDEO) on sale for $5/gallon! So if you're only going to run 5k miles, or even more in some applications, do you really get 4x the "protection" in wear metal reduction for 4x the price increase? There is resounding evidence to show that is not the case; often premium oils are not in use long enough to warrant the added expense.
You can likely get an increase in fuel economy by running a thinner HDEO. I personally run Rotella 10w-30 in my Dmax. I've had no issues so far at all. Some people fear a thinner oil in diesels, but I believe they are the dirty little secret that few are willing to experiment with. I for one am not afraid at all. Still - the fuel savings is minimal and hard to quantify. I just do it to throw the nay-sayers a curve ball, and prove that thinner HDEOs are just as capable in UOA performance.
Part of the reason I first questioned you is because you mentioned Mobil One (Mobil 1), Rotella, and Schaeffers. Well, to me, Mobil 1 is a general product line indicating their "synthetic" products. It refers to their PCMO, HDEO, and even gear lube products. Perhaps you meant Mobil Delvac 1, their PAO based engine oil. Good stuff. (AKA Mobil Turbo Diesel Truck TDT). But then you mentioned "Rotella". That, too, is a product line. But around here it generally means the conventional "dino" oil. If you were referring to the "synthetic" Rotella, then that would be "RTS" - also good stuff; a group III with a lot of VII. Then you mention "Schaeffers"; they have both semi-syn products (the 7000 series) and full synthetic products (the 9000 series). That is why I stated you need to be more specific in talking about these products. It's hard to show you the pros/cons when we really have a difficult time knowning just which products you're comparing. I would have interpreted your first post as comparing a PAO ("Mobil One") to a conventional ("Rotella"); not really a fair comparison because they are targeted at different marketing levels, and have great price disparity to show it!
You mentioned the "B" word ("better"); I hate that word because it is so mis-used and mis-understood here on BITOG. Well, "better" means different things to different people. You must decide what "better" means to you. Is it all about wear protetion? Is it about value? Is it about ease of service? And so on. So many different things play into each individual's perception of "better". I personally choose a set of criteria, then rank order them by priority, and that helps me decide what's "best" for me. But that may not be "best" for you.
We don't even know what vehicle/engine you're running. I presume it's a new-generation on-road vehicle, because you mentioned that you're bound to CJ-4. Well, CJ-4 oils used in conjuction with ULSD fuel have been showing very good UOAs. They don't fare quite as well with LSD, but that's understandable due to the sulphur issue. You mentioned a preference for thinner oils. OK, here goes ... for a "shoot from the hip SWAG", I'll go out on a limb and say for anything short of 7.5k mile OCIs, you could run a dino HDEO 10w-30 in the Delo, Delvac, or Rotella products. They are a bit harder to find over the 15w-40 grade. But they're out there; you just have to look, or maybe order. If that's not your cup of tea, then by all means, choose something different. After all, it's about you being comfortable with your choice, not mine. There are guys and gals out there running Amsoil for 5k mile OCIs; foolish in my opinion. But, and I don't say this to be glib, it's not about me, it's about you, and what you want.
Unfortunately, people often confuse "wants" and "needs" ... Choose wisely.
