All gens are good, i have old and new. You have variation in the trigger pack and the older ones will be more desirable to some people although the "reason" is not practical.
There are 3 or 4 configurations for sight that I have seen - white ring, black ring, tri rail, and just iron sight with...
They are all good. Some prefer the rail version although I like the ring site with an illuminator add-on.
the trigger pack gets special attention for early ones (g1-2) but when you find out why you realize the limited practicality of the difference.