looking for ideas on must have classical music

Hello classical devotees!

A friend had me rip quite a few of his CDs for his trip abroad. most were classical, and many were like 'best of' compilations. one or two were whole symphonies.

armed with these at least and no others I felt it time to wade into the classical waters and increase that genre in my library.

what then, are your fav, 3 or 4, go to, gotta have composers, movements, and or conductors out there on CD at least?

if also available in HD or otherwise, please point towards them as well, if you don't mind.

your input is sincerely appreciated and this input will initiate my list for current and future additions to the catalog, so again, thanks very much!!

Incredible feedback and i am extremely grateful for all of it.

all have my most sincere thainks.
One of my favorites is Tchaikovsky‘s violin Concerto in D.  I have a few versions.

Another amazing collection of work to consider is the entire collection of Beethoven’s piano sonatas played by Mari Kodama,  hi-Rez and high fidelity recording available by pentatone classics.

Vivaldi’s four seasons is extraordinary popular and for good reason, it’s quite good!

The Bach cello suites by Yo-Yo Ma. He has recorded it three times in his career, the most recent one just came out last year and it is excellent.

 Check out anything by Julia Fisher on pentatone.

Also check out some of the Wilson audiophile  recordings available at acoustic sounds.

good luck, have fun!