Several ways to answer this question. To me it comes down to value- what will sound better for a given cost. My answer is generally vintage. Digital and Class D aside, I don't think much has changed in audio design- only degrees of refinement. Circuits and designs are mostly updates of previous equipment. However parts quality in new equipment or in replacement parts is generally much better than what was available 30-60yrs ago. What is means is that a vintage component, carefully rebuilt using new high quality parts can sound much better than when new. That opens up the other variable- cost. Purchasing used, then carefully restoring is almost always more cost effective than purchasing NIB. Consider the following system:
2pr of KLH 9 Electrostatic speakers
2 HK Citation II amplifiers
Marantz 7 or ARC SP3a
Garrard 301/401 with SME arm, and Ortofon SPU cartridge
This system will get you to the 90th percentile of performance at a considerably lower cost than anything new (or recent). Caveat is that all components are fully and carefully rebuilt.
At the other extreme, a wonderful sounding system can be assembled around a rebuilt ST-70 and PAS3 (Val Alstine Super PAS 3a), a pair of ls3/5a speakers, and a Rega P3 TT with a Shure V15iii or V cartridge with a Jico Stylus.
One area that I do think has shown improvement is speaker design and implementation. Computer modeled design, using better quality drivers and crossover components results in much better sounding (and more accurate sounding) speakers. While there is much nostalgia for a pair of vintage JBL L100 or Large Advents- they still sound muddy and imprecise after new crossover parts are installed- and absolutely horrible if "all original". Original driver material design inhibits transient response and adds distortion when driven to high SPL.
FYI- my system is a combination of vintage and new. And would have a cost in the mid 5 figures if I had to purchase everything new.
Linn LP12- ITTOK LVII -Cirkus/ Hercules II PS / Stack Serene chassis, top/bottom plates / rebuilt Denon 103D (Soundsmith Ruby Line Contact)
Technics SP15 / AT 1503mkIII / mono modified Denon 103
ARC SP-10MKII
Mac MC240 Restored
(or) Luxman MA88 monoblocks
KEF LS50