Aldi, then Lidl, then a bit of a gap to Tesco. Aldi/Lidl don’t have full service ecommerce grocery offer, Tesco does; so for the same basket delivered you have to pay £10 more (plus a delivery fee of £1-£6 on top, although most frequent grocery ecommerce shoppers pay ca. £12 pm for a delivery subscription which covers up to one order per day, min £40 typically). Tesco also slightly inflates ecommerce prices as the cheapest lines (intended to compete with discounters) tend only be available in larger stores, not online or convenience format
“Which?” (UK Consumer association, similar to "Consumer Reports in the US)
I had an interesting conversation with an Aldi Area Manager in Ireland recently. The average number of employees needed to run an Aldi store at any given time was 2-4 with no more than 12 staff on pay roll. In a equivalently sized Tesco they would need 18-40 with more than 150-200 Staff on payroll. Incredibly efficient business model.
Those Aldi numbers only work for a store which is 100% self service tills, probably one of their smaller formats (and interestingly, match the staffing model for Tesco’s attempt to enter the US, Fresh & Easy Neighborhood market).
Older/larger ALDI stores have 6-8 staffed lanes which are all open at peak periods, so would need 6-8 in the shop, obviously
I think the Tesco numbers are a bit off, though. Off peak will have 6-8 “on shift” split between serving and stock management (direct observation of a similar sized Tesco in the UK that I visit regularly). Peak a bit more (staffed till lanes). That’s for a store that has 10 staffed lanes, 10 self serve (and also “scan as you shop” wands), with 1 or 0 staffed lanes open off peak (plus customer service for lottery, tobacco, money transfer etc. which Aldi does not do). Obviously bigger stores will have more, and Tesco may have more part timers hence more on payroll.