Depends what you want...
The 4AG is too small IMO, the 18RG is quite rare, the 3TG is also quite rare, 1ggte/2jz/1uzfe are all quite difficult involving quite a bit of wire work... and the 3SGTE will be very very difficult to mount up because they all come in transverse set-ups only (plus has a lot of wiring). Basically, just about anything EFI would be quite difficult to do...
I'd personally go with the 3TC. With a bit of build-up, those engines can make a lot of power/torque and they are bulletproof...
Other mentionables... 20/22R hybrids will probably be the easiest... and they do make good torque/power also...
The 4AG is too small IMO, the 18RG is quite rare, the 3TG is also quite rare, 1ggte/2jz/1uzfe are all quite difficult involving quite a bit of wire work... and the 3SGTE will be very very difficult to mount up because they all come in transverse set-ups only (plus has a lot of wiring). Basically, just about anything EFI would be quite difficult to do...
I'd personally go with the 3TC. With a bit of build-up, those engines can make a lot of power/torque and they are bulletproof...
Other mentionables... 20/22R hybrids will probably be the easiest... and they do make good torque/power also...