Given the masses of reissues, that's a touchy question and I doubt it is easier to answer than it was 21 years ago when the discussions in THIS thread were "hot".  I've wondered about this myself. At any rate I think it MUST be one that goes across label boundaries. Ultraphone/Swing/Decca/Columbia/Rhythme etc. all would have to be included, regardless of who "owns" what. And then it all depends on the programming/compiling philosophy: Will it be Django Reinhardt with the QHCF and/or his solo/trio/"Django's Music" recordings only or will his sessions with other French band leaders (Alix Combelle, Philippe Brun, André Ekyan etc.) and visiting US musicians backed up by French groups (where Django always made important contributions IMO) be covered as well? Back in the vinyl days when I started out, the "Djangologie" series of some 20 LPs by EMI/Pathé probably was the most comprehensive and best-organized one. But of course it was limited to the labels linked to Pathé. And these were too much for my student funds anyway ... and I already had some on individual other LPs and could not afford dumping these. Later on (in the late 80s) I bought this 8-LP set on Affinity (UK) which gives a good cross-section (including his very interesting recordings with visiting US jazzmen) but is not comprehensive either, of course:  https://www.discogs.com/release/5952389-Django-Reinhardt-Django Over time I picked up most of those LPs from the Djangologie series that more or less fill the gaps left by this Affinity box. Plus some "outliers" such as the sessions from Belgium, Italy, the session with US musicians from 1945, etc. But if I wanted to be still more comprehensive yet I'd have to almost start from scratch and get the Frémeaux CD series - as the "Intégrale - Saison 1 to 3" box sets which include 40 CDs. Which from all I've read and heard would be the most definitive multi-disc compilation today. They are listed at a shade over 60 EUR per box set on Amazon - which sounds like a fair price. And above all a way better deal than buying twenty 2-CD sets. https://www.amazon.nl/s?k=Django+reinhardt+Intégrale+Frémeaux&crid=1DJ95NVEHL3SM&sprefix=django+reinhardt+intégrale+frémeaux%2Caps%2C89&ref=nb_sb_noss BTW, talking about value for money, some years ago I picked up the below P.D. set of 10 CDs secondhand at a special sale locally for the huge amount of 1 (one!) EUR:   https://www.discogs.com/release/4287199-Django-Reinhardt-Djangology If found very cheaply, it is an OK gap filler for non-completists. It includes most everything of the studio recordings from April 1937 to July 1943 (search me why they cover this time span), and the fidelity is good. Sure, its presentation is basic, no session details at all, but at such a minimum investment this can be overcome if you have a decent Django Reinhardt discography (which I think I have). And at any rate, working your way through his discographical work to see what you have and don't have on any given multi-disc set (below the level of the Freméaux packages) and where you can fill any remaining gaps most efficiently can still be a long-winding affair. Better not to be a completist ... 

next and playing now:  

Marc Copland Solo: Time Within Time. hatOLOGY 619 [Switzerland 2005]