There's pros and cons to both sides. Group I and II conventional oils have higher aromaticity, solubility, and pressure-viscosity coefficient at the expensive of reduced oxidative stability and thermal stability. Group III and IV oils have excellent thermal stability, oxidative stability, and shear stability at the expense of lower solubility and pressure-viscosity coefficient. Group V oils are all over the board depending on which one you choose. The "boutique" oils tend to come with unique additive packages, usually with much more friction modifier, anti-wear, and sometimes more detergent additives. This sometimes means a higher temperature requirement for miscibility and additive activation depending on how it's formulated. A daily driver that never sees over 230*F pan temperature will most likely never see a benefit.
I've learned a lot about this recently in testing with high horsepower, high rpm racing engines. The oil that, on paper, appears dominant doesn't always work out that way in the field. A drag racing engine running for less than 2 minutes at a time with <180*F will want a very different oil chemistry than a NASCAR cup engine running at 8000+ rpm for hours straight with upwards of 360*F oil temps exiting the bearings. I say this to get to the point that every oil has its ideal purpose, and sometimes the boutique oil may provide no additional benefit if your particular application doesn't fall in line with what the oil was designed for.
For cleaning, you need solvency. Esters and naphthenics dominate this category, but it can come at a price of reduced thermal stability and oxidative stability. Esters also have high surface affinity and like to react to base metals, which can increase wear. The next best thing to group V oils, for cleaning, would be group I. It would be nice to see a budget-minded, cleaning specific oil that's entirely group I in like a straight 20 or 30 grade for 1500-2000 mile intervals.
Detergent additives don't do anything to varnish and sludge. Detergents work by neutralizing potentially damaging acids to prevent them from becoming catalysts for oxidation. They exist to keep the oil clean, not the engine.
