Nymphenburg or Residenz?

The Botanical Gardens are adjacent to the Nymphenburg Palace. We toured the palace and grounds and the Botanical Gardens, but not sure how that would play out in late March. There were several greenhouses. I doubt much other than very early spring bulbs may be flowering, but don’t really know. The Residenz (we only did the interior) was spectacular we thought, so depending on the weather I’d say you couldn’t go wrong. Safe travels.

While both are excellent , the interiors in the Residenz are far more extensive . The Treasury or " Schatzkammer " will take your breath away ( look for the exquisite St George statuette , carved of ivory and bedecked with a heavy slather of precious gemstones ) A full day there is a must. Two high points at Nymphenburg , besides the gardens , are the collection of Nymphenburg porcelain , and the stunning " gallery of beauties " https://en.wikipedia.org/wiki/Gallery_of_Beauties

I'd say if the weather is decent, Nymphenburg, hands down.

As for the Residenz, my opinion is that there is too much of it. It was interesting at first, but it eventually became tedious. You can only see so much silverware, pottery, and gaudy rooms before it becomes tiresome.

The are two interesting alternatives to the Residenz if you stay in town.

The Deutesches Museum has some really interesting exhibits, particularly the aviation exhibit, and also the mining exhibit and the bridge building exhibit. If you try to see everything, it to can become tedious. Look carefully at the map to see what you really want to see.

Another interesting museum in town is the Münchner Stadtmuseum, just south of Marienplatz. Every time I've been there (2x) they have had interesting historical exhibits about life in Munich hundreds of years ago, and the growth of the city over the ages.

You could wait until you're in Munich to decide. If the weather is nice, I think Nymphenburg would be a good choice. We were there in October 2015, and the fountains were turned off, but the grounds were still gorgeous. I didn't realize that covering statues was a thing. If the weather's not so good, then Residenz it is. You can eat and drink at the Spatenhaus on the same square as the Residenz.

Neither one requires advance reservations.

Enjoyed the Residenz and it's easily accessible in the heart of Munich so I'd definitely recommended it. We did drive by the Nymphenburg on the way to Dachau but didn't go inside.