Dell is far better with parts availability, although (much as I personally don't like them), Apple is better than either.
Really? That's too bad - I had to replace the fan on my Lenovo T500 some years back (~2011) and they had sent one overnight-by-10:30 (and it was pretty inexpensive, too). It certainly made an impression.
I guess back then IBM still ran the parts and service business, even though Lenovo had taken over the manufacturing and marketing several years before.
I've read stories on /r/thinkpad of it being a bit hit and miss sometimes, but they've been very good to me for the last 10 years or so. Far better than my experiences with Apple (not dealt with Dell).