the intake gaskets can also leak into the cylinders - that's far less problematic in some ways...although that pic looks really b ad.
Depends what you mean and what are your goals (more original, more modern, cost, ease, minimal wiring, power).
For most people, any engine they want is going to require wiring and fabrication so it's basically all the same.
EJxx is the standard modern upgrade.
In the US it's the 1990-1998 EJ22 is the preferred option. Easiest wiring, more reliable, significantly more power, readily available parts.
A non-turbo would be the closest in wiring. that would be as close as you can get to "plug and play" with minimal wiring work but you'll still be looking at diagrams to ascertain differences. I've put a non-turbo EA82 into an EA82T XT Turbo and gotten it to run before with no wiring work at all.