Lots of cool engines out there to choose from, depending on what you’re doing with the rig. Some are more problematic than others. Some have lots of trade offs in one or more directions.
I’m currently into the LS engines for a variety of reasons. Power:weight ratio, serpentine belt setup with separate AC belt, distributor-less ignition, plentiful parts, aftermarket support, open programming, starter hangs on the outside like it should.
Cons include that they run hotter and generate more heat, require a high pressure fuel system, have all your potentially problematic electronic components, require some form of VSS setup, need additional hardware and plumbing for the cooling system.
Lots of guys have overcome the conversion hiccups and couldn’t be more happy with the results. Little wonder that they are replacing SBC’s as the new V8 go-to powerplant.