For example, if your budget is 40k, then amps and cdp from brands like Cambridge Audio, Marantz, NAD (all budget); speakers from Wharefdale, Mordant Short (budget), will give you better SQ than Sony, Samsung, etc., IMO.
Are you the person to stretch your budget for the sake of SQ ?
For sound quality you better look at Philips, Samsung or LG. I never recommended the Koreans at one time but they have now gone way ahead of Sony.
A Hi Fi will give you the option of Cassette Deck & CD Changer. There is no other difference. 5.1 Home Theatre or 5.1 Mini Hi Fi will sound more less the same for movies.
A 5.1 Mini Hi Fi will sound better as the main speakers are proper two way speakers instead of satellites found on a 5.1 Home Theatre in a Box or HTIB but the options for a 5.1 Mini Hi Fi is limited to Sony & Philips.
As mentioned by another member, doubling your budget will take you to another level in sound quality. A much higher level but then keep in mind that you are going to be spending a lot more.