My take, fwiw:
DA:O - Very solid game but highly derivative and very disappointing as a result for Bioware's much ballyhooed (by them) first world of their own
DA:2 - Lazy game that isn't as bad as its reputation, but still isn't very good.
DA:I - Enough good content in here to make it the best of the series, but bloated with tons of filler…. might still be my favorite
ME1 - This is the overrated one. Short, terrible combat, recycled assets, tedious despite its short length, no meaningful choices (granted, that wasn't evident until later, but they were still meaningless), terrible inventory system
ME2 - best of the series; better companions than 1, more fleshed out/longer, better combat than 2
ME3 - best gameplay, decent all around other than the admittedly beyond weak original ending. I never played their revised ending.
ME:A - Suffers from the DA:I bloat, but again, a solid game with enough good stuff to produce a series highlight if it was stripped down. The backlash was way out of proportion to its quality.