Memories go beyond presents
Are the two mutually exclusive?
Surely memories can be bound up with presents too....
i dont like either extreme really, I loathe the " my child was happy sucking on the lump of coal, arnt we amazing" and the " lets spend thousands in toys r us"
Its possible to have a lovely xmas, with a pile of presents!
For the first 3 to 4 years of DD life she got xmas from car boots, pounds shops and freecyle, Indeed her best present one year was an angel dress I got for a £1 at a car boot, and another year it was a huge carrier bag of lion king toys I got for free.
She spent most of that winter lining them all up in different poses round the house and they were FREE. But it seems that doesn't matter to some posters, that even if they were FREE they would have wittled that large bag down to maybe ONE toy 
Exciting and lovely toys does not = expensive plastic crap.
However xmas to me also means, something really exciting under that tree, that expectation. I have wonderful xmas memories of waking up with a huge doll on my bed, or going to the tree and there, glistening with the tinsel, and the embers of the fire a brand new shiny silver and white racer bike!
Now my DC are older I spend more on them.
OP back to your question its not an issue of how many for me. Its more, what are their interests this year, what will last through the year till next year...whats fun, whats educational etc.
So I have got a john adams hot wires set, which is electrical, and be great learning tool as well as lots of fun, she can create loads of working things with it.But it was expensive, For fun, a furby, for education, those historical usborne sticker books which teaches them about historical dress. She will get some Greek Myths books as she is really into them at the moment. My DD comes to things throughout the year too, so it keeps her going. Loads of books too, this year wolves of willougbhy chase.