Walmart is a best place for shopping. OR
Walmart is a good place for shopping. OR
Walmart is the best place for shopping. or
Any difference between 'a best' and 'the best'??
"...is a best place" isn't correct.
a good place means there are many good places.
the best place means only one is the best.
a best place sounds like there is more than one best, which isn't logical.
(Edited to add: Actually, there are situations in which you can have "a best" - that would be when you have categories of things, with good, better, best. Like sheets or hotels. But it will still sound funny.)
[not a teacher]