Definitely easier without the trans, even with a leveller, bit more fiddle to get under and unbolt the trans etc, but it comes down to how patient you are, and if you are not to precious about a few scratches in your engine bay leave the trans on.
And if it is getting a full rebuild, pull as much stuff off the front of the engine as possible, fan, pulleys, pumps etc, just gives you a bit more room to play with...,