In general the advice to go for the left seat is good, however I would evaluate carefully the potential future of both companys involved.
Is the 767 operator well financed and established with solid growth potential ?
if not, the upgrade is the only choice, if it is, a foot in the door could be well worthwhile.
The same principle applies to the E 190 operator, and, can you move up to larger aircraft within this company (assuming this is your long term goal)
While Command time is invaluable, rarely will it allow you to move to a new company and stay in that left seat.
Some of the previous posters (rightfully) endorse upgrading as soon as possible as they did in their Companys, however they were able to stay within that same company and move up to larger aircraft
Worth considering..