Construct 3 will eventually be 100% better than Construct 2.
At present the two biggest reasons to use Construct 3 are:
-It works in a web browser (pretty neat!)
-It has better export methods for mobile (same performance)
The two biggest reasons to use Construct 3 are:
-It isn't a subscription
-It has more plugins available
(and bonus: C3 can import C2 projects anyway)