Many, many considerations for what's best deck for your uses.
Some decks have lower noise if mic power is NOT used.
Some decks have a lot of high frequency type noise that might 'color' certain type sounds, and some decks have better sounding mics (which I DO NOT test).
I would lean towards the R-09HR for likely
having the best (user reported) for music mics, and if you are using a self powered mic, the mic powering noise is not an issue.
However, for lowest high frequency type noise, the D50 and LS-10 are noteworthy.
Ya, it's a tough decision.
Below is a collection of noise plots-to-ponder.
Links to deck model discussion threads/reviews at: www.sonicstudios.com/tips.htm