My home town has a smallish Lidl, and there is an Aldi a drive away. I don't drive, so use the Lidl more, but the localish Aldi is a lot bigger, so has a bigger range, particularly in the 'aisle of dreams'
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Having said that, the bakery products at Lidl are much better than Aldi, and their frozen and chilled foods are more varied. That may be because of the immediate catchment areas - the nearest Aldi is in a poorer town - but Aldi seems to have lots of chips, potato products and assorted pizzas, whereas Lidl have foods from a different country each week or so.
If the local Lidl were bigger I would love it, and would definitely make it my regular supermarket if they delivered.