I visited my husband multiple times on my Esta without any issues. DO NOT apply for a visitor visa if you are eligible for an Esta.
The reason I was able to successfully visit multiple times while my CR1 was pending, was because I had strong ties (stable job, house) to my home country and couldn’t have long visits because of those ties. If you apply for a B visa because you want to visit longer, you show that you don’t have strong ties, and together with your immigrant intent, you’ll probably face a denial of your B visa.
Keep your ties strong, your visits short and DO NOT apply for a B visa.