Agree with the Seafort Saga reccomendation (even got a signed copy of Fisherman's Hope), but IMHO they get considerably weaker in the last 2-3 books.
The entire religion / duty thing also gets a little wearing if reading the whole lot in order.
Peter F Hamilton is also a good shout, but he can have an awful lot of wheels spinning at any given time, which sometimes makes things somewhat confused. The latest lot (Salvation Sequence) has this problem in spades- basically he's getting too clever for his own good
Cixin Lui isn't at all bad, but all his work really suffers from translation / cultural issues, which push it from great to just good in my eyed.
Other thoughts-
Try the Crystal Singer trilogy by Anne McCaffrey. This is self-contained, and is IMHO some of her better work. Closer to light reading, but very good.
Elizabeth Moon's Vatta series is another one to try- Again I think some of her better work.
Wouldn't necessarily rank her close to Hamilton, Asimov etc. but rather decent light reading.
Really offbeat / less known would be the Song of Phaid the Gambler by Mick Farren (Doesn't even appear to be available as an eBook), but absolutely worth trying, although may be marmite.
Probably read *everything* in this thread and a lot more ranging from utter dross to quite decent.
At the end of the day though, best thing I can say is experiment.
Something I've read and liked might be nowhere to your tastes, but restricting yourself never gets you anywhere
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