Loire in April - Villandry Chateau?

Everyone has their favorites, but some of the chateaux in the Loire that are widely considered to be among the top ones worth a visit include: Chateau de Cheverny, Chateau de Blois, Chateau d’ Azay-le-Rideau, Chateau de Chenonceau, Chateau de Chambord, Chateau de Chaumont-sur-Loire, and Chateau Royal d’ Amboise.
Two of my favorites are Chenonceau and Cheverny.
One big plus of renting a car in the Loire is (1). You’ll be able to visit more chateaux in a day than public transportation allows and (2). you’ll drive past chateaux you recognize from photos and be able to see them, even if you don’t stop off to enter them.
Have fun in France!

Erica, we were just there this past fall. IMHO, the three unmissable chateaus would be Azay, Montresor plus Gaillard--each for very different reasons.
Azay on a nice day presents as magnificent and manageable. The crowdage is less than elsewhere. In town, one might dine at Odettes, the local fave crepe place (reserve ahead). Azay town itself was disappointingly underwhelming, tacky and kitschy during its annual fall fest.
Gaillard was everything that we had hoped, a much quieter place removed from the hordes back up at Amboise's main castle. One could do a two-fer by first visiting the Da Vinci muse, then head on foot 10 mins further to Gaillard. Gaillard has an OK interior but it is the unique citrus-flavor (literally and figuratively) that makes that sympa chateau and its pleasant park/jardin so welcoming.
The Gaillard cafe is built into the castle back wall. They do self-styled salad nicoise plus your choice of three different freshly-squeezed citrus juices. *DO NOT miss their famed orange cake--worth crossing an ocean for!
Bonus: the cafe also sells a wide variety of top-shelf jams and marmalades. The latter would make superb gifts.
Btw, the walk from central Amboise to Gaillard is a very pleasant, real-McKoy French semi-rural stroll.

Finally, Montresor. It is tiny. The Brit gal that runs their Tourism Office is exceptionally friendly. The boulangerie claims to have invented macarons. There is a tavern/cafe but the big foodic news is 'Ecole Gourmande', a VG newish fine-dining restaurant. It is a one-man show and his inventive dishes are sure to satisfy. That restaurant is right by the famed Balcons or footpath that takes one across the bottom of the village with views up to the chateau to die for. Think horses, countryside and like that. Go on a sunny day.

Two bonuses await visitors. First, the historic carding hall has a free permanent display of the unique fused-glass art called 'gemmail'. One piece was created by Gaugin.
The other bonus would be the remarkable views looking towards the church and also out to the hinterland, as seen from the paved path leading from the village center up to the Chateau. France Profonde indeed!
Hope this helps.
I am done. the Loire

Of the six that I have visited (Chaumont, Chenonceau, Amboise, Villandry, Château d'Ussé, Chinon … plus Clos de Luce), I’d comment …

• Chaumont. Lovely gardens. Nice pairing with Chenonceau for reasons of history: Henri II, his wife Catherine de Medici and his lover, Diane de Poitiers. Upon Henri’s death, Catherine compelled Diane to surrender Chenonceau in exchange for Chaumont.
• You’ve been to Chenonceau, so no need for further comment.
• Amboise. I thought Clos de Luce was more interesting. Leonardo history and some of his designs — bridges, Archimedes screw and more in the gardens. Good for kids of most ages.
• Villandry. Lovely gardens … and furnishings. Quite formal.
• Château d'Ussé. Lovely chapel. Nicely furnished. Sleeping Beauty story, so great for younger children.
• Chinon. A bit of a ruin. Commanding view and great history of Joan of Arc and her successful effort to persuade Charles VII to allow her to lead the French against the English to drive them from France.

Chaumont and Clos de Luce have the advantage of proximity, as well as the history, context and gardens, as mentioned above.

Nearby Villandry is Savonnieres, a wet cave that we found interesting

We visited Villandry and Chambord last April, right after Easter, which was April 20. The gardens at Villandry were nice, even so early in the season. No crowds either.

If spring comes early again this year as it did last year, Villandry would be a good choice for their gardens. However, Azay-le-Rideau is in such a beautiful setting.

You don't necessarily need to choose- we did a day trip from Tours a few years ago with a very small group that took us to Azay-le-Rideau, Villandry, Cheverny (the one with the dogs and the "soupe de chien"), and Chambord. It didn't feel rushed at all and I felt like we had plenty of time to see everything. (The tour was just for the transport really, once we got to each place we were on our own.) The only exception was we didn't get to go inside Villandry, but the main thing to see for that one is the amazing gardens. If you're looking to just visit one, I would go with Chambord just to get to experience da Vinci's architecture in person. But honestly I think you'll enjoy any of these.

We visited ones Kenko already mentioned and we had a rental car; Chateau d’ Azay-le-Rideau, Chateau de Chenonceau, Chateau de Chambord, Chateau d’ Azay-le-Rideau and Chateau Royal d’ Amboise.