A few thoughts,
The 124’s are probably the most user friendly (Clutch / strobe) The integral arm board to the chassis is perhaps a little misguided in terms of vibration transfer- the E50 motors lack a little ooommf - The MKII non mag platters were useful for some carts however the heavier iron platters can sound better. The bearing arrangement does not have any damping (ball bearing thrust) Proper set up can be a little finicky (belts, thin idler wheel, isolation mushrooms, thin pressed aluminum top platter.) The sound of a well sorted example is good. The best I’ve heard is without the top platter (Tenuto on duty) with the arm set to the plinth (not mounted to the arm-board frame.
The 301 was designed prior to the take off of STEREO (Designed 1953, released 1954) The grease bearing has a sloppy tolerance to allow for the grease, the motor is a lump which produces plenty of torque. The BBC changed over from grease to the later 301 oil bearings and some changes were made to the motor in an attempt by Garrard to ‘keep up’ with he demands of STEREO. In summary early 301’s are good as a MONO set up later 301 oil bearings better with STEREO.
The 401 (whilst not to everyone’s tastes visually) was the Garrard engineers idea of improvement - Switching set under the chassis, user friendly strobe, ribbed stiffer chassis, Cast iron screened motor with better bearings (Runs quieter with less torque) Many other aspects of the 401 are beefed up versions of the 301, the spindle bearing’s thrust pad is a damped dome of sintered bronze - again an improvement designed by Garrard for STEREO transcription / listening. The 401 falls down due to losses, cosmetic cutbacks initially from market forces then by the slash and cash in directives from the ‘then’ new owners of Garrard (Plessey) Personally I prefer the early 401’s (Twin spark suppressor types)
The Audio Creative Groovemaster MKII is a nice performer £ for £ in comparison with many of the 12" offerings out there today. It’s effective mass is 22g well suited to SPU / IO / Koetsu fans