Many of music players in Linux can play FLAC file out of the box. Of all these, I have tried all the big names Rhythmbox, Banshee, Amarok, Exhaile, XMMS, Audacious, JuK. Of all these XMMS and Audacious have the WinAmp look, so it will take you less than 2 seconds to figure out where things are.
If you are more into organising your music files, then try Clementine and/or Guayadeque. I've been a long time FLAC-ophile and I love Clementine the most, but it's more like music library management/player. However what i like most here is Clementine can work seamlessly with the embedded cue sheet. So if you rip your gapless cds (imagine concerts or some Pink Floyd's stuff) as one track flac file with embedded cue, Clementine will read into the cue file and list the songs as show on your CD. The 'big name' ones can't do this. Bad thing about it is, first time library load takes quite a long time. Afterward it just constantly monitor the library.
I love MATE desktop (Samsung N150)