Sort of hamstrung by the fact that there's a small Aldi in Ely (5 miles away) but the nearest two Lidls are either in March (a small one) or in Huntington (a much bigger one), both equating to something like a 40-mile round trip.
I'll go to Aldi in Ely for the things Tesco either doesn't do (big blocks of what I'll call "cooking" cheddar) as I can't be doing with buying tiddly packets for something I use a lot of, or doesn't do very well (Aldi's basic corned beef is light years ahead in terms of taste and texture, their peppermint tea is 75p cheaper on 40 tea bags and the venison burgers are lovely). But I wouldn't do a weekly shop in there as I find the lack of choice rather frustrating.
I do actually prefer Lidl over Aldi, but I'll only go if I'm already in the area for something else e.g. on the way home from a cat show. Other than Christmas, where I'll go to the big one in Huntington and stock up on their festive stuff, as some of the things (spiced biscuits, marzipan, Dutch gingerbread and some of the cheeses) are very good. Again, wouldn't do a weekly shop in there, but it's good for the bits I can't get anywhere else.
And tbh, they're not really any cheaper than the "big four" supermarkets if, like me, you largely buy own brand anyways - you get that perception because quite often the packs of things are smaller. If you compare price per kilo on things, there's very little difference when you spread it out over the cost of a trolley full of goods. Some things are genuinely cheaper e.g. the corned beef I mentioned, but other things, particularly some of their food "special buys" are actually more expensive. So really, it all comes out in the wash at the end of the day.
Also, Aldi's milk chocolate is bloody ghastly. It's ridiculously sweet, even more so than Cadbury's dairy milk.