Neither
Derek Cohen (in Perth, Australia)
I lack a shoulder plane. Attempting to build the Chris Schwarz saw bench, with the funky 10* angle cuts, and it became quite apparent that my paring skills suck. All of the legs came out wonky. Apparently, it's time to invest in a shoulder plane. But I seem to recall a post sometime back where someone recommended a rabbet block plane as a more useful tool than the medium shoulder plane. Any advice?
Gerald, I occasionally use a shoulder plane to tune tenon shoulders, but mainly use a chisel here. I find shoulder planes more useful for fine tuning - sometimes making - rebates, especially small rebates (such as with slipped drawer bottoms).
To create an accurate tenon shoulder, I saw a smidgeon off the scribed line, and then use a chisel in the line. A shoulder plane is used when there is too little to use a chisel (where there is too little reference area).
Cheeks rely on being square and parallel. A plane (of any type, including a rabbet block plane, and especially a shoulder plane) is vulnerable to planing away square. If you need to ensure square, use a large router plane. I do so, and have never needed an outrigger to maintain flat.
Mostly I fine tune cheeks with either a wide chisel or a rasp. I would consider these for more confident workers, and you need an eye to keep all surfaces parallel.
My LN rabbet block plane comes out when I need to level and true up the insides of drawer cases. A wide shoulder plane might not have enough clearance (that is, it is too high).
Regards from Perth
Derek