I am new here (and relatively unfamiliar with open-source firm-ware). Please bear with me

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I want to add my entire cd collection (about 150 cd's) to a portable player in FLAC format. I also want to add live shows recorded in FLAC from archive.org
I do not own any portable music device. I want to buy one that supports RockBox (solely for FLAC compatability). I have looked at the supported list, and cannot decide which device fits the bill for me.
1. Large storage size
2. User-friendly change in firmware.
Thanks for any input (sorry if this is the wrong forum).