Without a doubt I'd say Coronet Peak. Been a few years since I've been down there but they have a large area for learners with good magic carpet. Even if you take the main lifts to the top there are many gentle routes back down for when you get a bit more confident. 

We're going down in August and partner hasn't been on the slopes in a LONG time so we'll be going there on day 1.

Cardrona or Coronet Peak would be my pick for beginners.

I would pick Cardrona - particularly if staying in Wanaka

I'm in Wanaka ATM.  I think Cardrona should be opening next week.  It's $130 for an adult day pass - so the price is getting up there.  So you can get the price down with multi-day passes, but need to book before 26th June.

Quite a few people around - more than I expected - but nowhere near "normal", which IMO is good - but local businesses may not agree.

If you're booking accommodation, use google to find motel/hotel, phone them to book direct - don't use booking.com and similar agencies.  Even if you don't get any extra discount, better the struggling business gets the 15-20% than some overseas owned agency.  FWIW, we're staying in a relatively basic but OK motel two minutes walk from town, off season book price is $180, booking.com had it listed for $115, owner discounted it to $100 - without haggling.

I loved Coronet Peak 30 years ago.  Now, not so much, way way too busy on nice days, long queues, pushy inconsiderate foreign tourist skiers.  But maybe this year will be okay.