There is no best. For comparison purposes I've just installed a Leupold FX 4 on a new Marlin 444 (a pretty good kicker BTW). It has a 4 inch eye relief (desirable to be sure) and exip pupil of over 8. I personally think that 4 power should be plenty of magnification for out to 200 yards with the new LeverEvolution ammo that I'm going to try. If you want a good variable there are tons, but I feel a smaller size (bell diameters of up to 36mm) fit the lever guns better. Look at the Kahles, upper end Elites 3200 and 4200 from Bushnell, Weaver Grand Slam (only as others are not great IMO) or the high dollar Zeiss and Swaros. Many choices out there.