reference recordings

If your question is based on sound quality, just about any of them. Hard to go wrong. The HDCD versions might be best if you have a unit which can decode them. If you are talking about performance quality, which performances are you interested in?

either jazz or classical

You could try Dick Hyman "Swing is Here" I think it sounds pretty good.

I only have it on vinyl, but I really like the Kronos Quartet - "In Formation" RR-9. I have quite a few others, but frankly, I'm not nearly as crazy about most RR's as some people - either from a recording or performance standpoint.

The one's on Arthur Salvatore's (who's opinions I generally find accurate) list are:

ARNOLD-OVERTURES-ARNOLD/LPO-REFERENCE RECORDINGS RR-48

EBONY CONCERTO-YEH/DEPAUL UNIV. WIND ENSEMBLES-REFERENCE RECORDINGS RR-55

FIESTA (REED/GOULD/NIXON/WILLIAMS/PERKINS)-DUNN-REFERENCE RECORDINGS RR-38

WEBER/BRAHMS-CLARINET QUINTETS-EDDIE DANIELS-REFERENCE RECORDINGS RR-40

check out the recordings to die for threads here.

I like the non-HDCD discs from RR just as much due to the clarity of the recordings-some of the best discs i've ever heard (the Helicon Ensemble disc playing bach/baroque is clear as a bell). HDCD is fantastic though- i like Trittico- dallas wind symphony with lots of percussion and brass. the problem with HDCD is the huge dynamic range- 1st you have to turn up the volume way higher than with regular cd's because of the hdcd filter, but then you have to keep your remote handy in case your speakers can't handle the really loud parts. i hear they are coming out with more titles now, which is very good news.

The Bruckner 9 is an outstanding performance as well as recording. One of my Favorite RR's. His Copland 3 w/ Applachian Spring and Fanfare for the Common man is a good recording and performance as well. Assuming you just want some generic classical recordings with excellent sound the compulation recordings with Eiji Oue and the Minnesota Orchestra (there are 5 of them I think) are excellent as well.

I have much of the RR catalog. If you have a specific Composer or recording in mind. Ask. Kind of tough to respond otherwise.

It's hard to respond to your question without knowing what kind of music you like, and it would help to know whether or not you've got an HDCD player. Here are a few of my favorite RR recordings:
(1) Strauss, Ein Heldenleben, Oue, Minnesota Orchestra, HDCD. A great performance of a great work, fully exploiting all the resources of a large orchestra as only Strauss could. Superb HDCD sound.
(2) Felix Hell, "Organ Sensation," Liszt, Vierne, Guilmant. This gets my vote as the ultimate audiophile pipe organ CD. If you want a real lease-breaker, if you want to test the depths to which your subwoofer can reach, this is the one. Terrific HDCD sound, with bottom end that will take your breath away.
(3 & 4) Nojima Plays Liszt, Nojima Plays Ravel. These precede HDCD, but don't let that stop you. Wonderful performances of great music by a master pianist, captured in magnificent sound.
(5) Eileen Farrell Sings Torch Songs. The first song here, "Stormy Weather," is the most perfect recording of a great vocal "standard" in the technical sense that I've ever heard. The vocal is backed up by a "just right" jazz combo, and the sound is impeccable: the group is right there in front of you in your listening room. (This song is also on the RR Jazz sampler.) This one is also pre-HDCD. Truly a reference recording.
Hope this helps. Happy listening.

i do have a hdcd

Holidays
&
Epiphanies
...the music of RON NELSON
Dallas Wind Symphony
JERRY JUNKIN
A PROF. JOHNSON HDCD RECORDING

You may want to try an XRCD dics. For example, Bartók Concerto, Reiner, Chichago SO. This is probably a version which is fairly close to the original analog sound.
Also have a look:
http://highdeftapetransfers.com/index.html

Reference are continuing to improve in sound quality. Choose anything in the last year or two that sounds interesting to you and anticipate being amazed and delighted; your expectations of recorded sound will be forever changed. The 'you are there' quality is more stunning on all the recent releases than the older but still excellent issues.