Unfortunately, I think every recording has a fatal flaw in terms of casting so it might come down to which characters/songs you most want to hear. I agree completely.
I think for the most part, the Tenth Anniversary Concert recording is a good place to start for your first recording. However, it is recorded live, so bum notes are preserved for posterity. Michael Maguire's Enjolras sounds strained and tired on this recording (he is good on the OBC), and Colm Wilkinson's age does somewhat affect his vocal control. Michael Ball is particularly resonant and emotional here-- this is his best recording-- and the Thenardiers are great. Philip Quast as Javert is widely considered the ultimate Javert (although I personally am not that fond of him). This is the recording with Lea Salonga as Eponine and Ruthie Henshall as Fantine.
The Original Broadway Cast is nice because the tempost are faster and the recording is smoother, but it's missing a lot of music. This is the only disc with David Bryant instead of Michael Ball as Marius, and his voice is very weak. Frances Ruffelle is a controversial Eponine because her voice can become very whiny-- she is the same Eponine on the OLC-- but she gives a powerful performance and the number of people who like and dislike her are about even. Terrence Mann plays Javert on this recording, and many people complain that his voice is too light and nonthreatening for the role. (I personally love him.) Randy Graff is really a powerhouse Fantine-- she's my favorite, though some people think her voice is strident. This is the recording where nearly everyone sings in an American accent, which can be good or bad depending on your preferences.
The Complete Symphonic is a good recording to buy AFTER you have one of the first two. It contains all of the music, so if you love Les Mis, that's great, but if you just kind of like it, the extra bits might become repetitive and irritating. Gary Morris plays Valjean, and I believe he's an American country singer doing a Colm Wilkinson impersonation. On some songs, he actually sounds really great-- he has a stronger voice than Wilkinson-- but most of the time he just sounds weird, like he's going to burst into tears. It's like Michael Cerveris singing in falsetto with a mouth full of mashed potatoes.
Also, Kaho Shimoda, Eponine on this recording, spoke no English learned her role phonetically. She has a very strong accent, and her performance suffers because of this. Anthony Warlow is a powerful Enjolras, and many people like his Enjolras the best. Philip Quast and Michael Ball are both on this recording, and I personally think Quast sounds a lot better here than he does on the Tenth Anniversary concert recording.
I only have a few tracks from the OLC, but Michael Ball sounds about twelve and Enjolras sounds like a weenie...
In my pants, she has burst like the music of angels, the light of the sun! --Marius Pantsmercy