Never heard of Metabrowser before, appears to be some sort of media manager and custom front end to windows media center but it looks like it's output compatible with XBMC and claims Boxee/Netgear too.
XBMC would probably be the best option as it's supported plus XBMC displays more fanart/coverart than Boxee does, (no idea on the NeoTV550) & lastly XBMC has skins so it can be made to look like other platforms. MediaBrowser seems like a xbox/metro clone and there are a few of those for XBMC already like Xperience
and this mod
of it to make it look exactly like the Xbox or another Metro style like this
The current well only XBMC box on the market from Pivos the XIOS DS
does not support, BDMV structure*, 24p or HD audio pass-through so that probably rules that out. If you rip the BDMV folder with MakeMKV to extract the main movie and can live with 1080p@60Hz with AC3/DTS pass-through then it might be an option.
* In the context of supporting BD Lite menus or simply playing the BDMV folder, you can go into the folder and play the m2ts files.
There are more XBMC boxes in development, Sigma Designs probably the sole remaining dedicated media player chipset provider demoed XBMC on one of their chips in September but when they will hit the market is unknown. They are the ones most likely to have 24p, HD audio pass-through, BDMV. Most Sigma players support that stuff though the ones currently available don't run XBMC so they wont be able to look like MediaBrowser, whether they can use the data generated by MetaBrowser is also up in the air. I'd look into the Syabas Popcornhour A400 as one candidate.
As to Boxee Box
* Boxee UI only no skins.
* No fanart only custom coverart and nfo data.
* 1080p@24Hz supported
* HD audio not supported (despite what you might read it's broken)
* BDMV will play but Boxee doesnt always guess the right video track.
* Boxee haven't updated the Boxee Box in months, they've abandoned it to work on something else.
As to Netgear NeoTV, these are also abandoned I believe.