Engine swap help for 88 nissan?

I have a 1988 Nissan Sentra E Hatchback - Manual transmission and I love the car. I had the car for over a year now and I have been going some repairs on it but is now thinking about swapping out the engine for something more up to date. Any thoughts or suggestions for what kind of engine I can swap into my car? Much help would be appreciated since I really don't want to sell it and get a new car. XD