I haven't played MEA because money + it sounds like it'll benefit from patches, but I don't see any real decline or anything like that. DAI is an excellent game if one with too much filler, and ME3 was also excellent aside from that ending.
Ratings:
BG1 1 *** (Probably have given it 4 or 5 when I first played it, but future games made it obsolete)
BG2 *****
NWN ** (*****) Two stars for the original campaign, 5 stars for all the player made modules
KotOR **** (Combat is really bad, or this would be 5)
JE ***
ME1 ***
DAO ****
ME2 ****
DA2 **
SWtOR ****
ME3 **** (Bioware's best combat since BG2, but the ending costs it a star)
DAI ****
Ratings:
BG1 1 *** (Probably have given it 4 or 5 when I first played it, but future games made it obsolete)
BG2 *****
NWN ** (*****) Two stars for the original campaign, 5 stars for all the player made modules
KotOR **** (Combat is really bad, or this would be 5)
JE ***
ME1 ***
DAO ****
ME2 ****
DA2 **
SWtOR ****
ME3 **** (Bioware's best combat since BG2, but the ending costs it a star)
DAI ****