Your original question was whether you should choose 'Best regards' or 'Regards.' Within personal, friendly correspondence I suppose that we could assert that there's really "no difference." When considering business exchanges, however, Forbes, a well-known, global company with a focus on business, consulted experts: "All of that said, here is a list of common and not-so-common email sign-offs, with commentary and notes from the experts. Best – This is the most ubiquitous; it’s totally safe. I recommend it highly and so do the experts. My best – A little stilted. Etiquette consultant Lett likes it. All best – Harmless. All the best – This works too. Best wishes –Seems too much like a greeting card but it’s not bad. Bests – I know people who like this but I find it fussy. Why do you need the extra “s?” Best regards – More formal than the ubiquitous “Best.” I use this when I want a note of formality. Regards – Fine, anodyne, helpfully brief. I use this. Rgds – I used to use this but stopped, because it’s trying too hard to be abbreviated. Why not type three more letters? OK if you’re sending it from your phone. Warm regards – I like this for a personal email to someone you don’t know very well, or a business email that is meant as a thank-you. Warmest regards  – As good as Warm regards, with a touch of added heat. Warmest – I use this often for personal emails, especially if I’m close to someone but not in regular touch."

Kind regards is also another option, there’s really no difference

There's really no difference. Use whichever you prefer. There are lots of ways to open and close emails, so don't feel like those two are your only options.

It’s a matter of preference. If you are feeling more friendly and helpful and personable, you might write “Best Regards” but either way is polite and professional.

The choice between "Regards" and "Best regards" at the end of an email largely depends on the level of formality and your relationship with the recipient. Here's a general guideline: "Regards": This is a more neutral and slightly formal way to end an email. It's appropriate for professional settings and when you have a formal or distant relationship with the recipient. "Best regards": This is a slightly warmer and more personal closing compared to just "Regards." It's suitable for professional emails but adds a touch of friendliness. You can use it when you have a relatively friendly or familiar relationship with the recipient or when you want to convey goodwill. If you're unsure, "Best regards" is a safer choice as it maintains professionalism while also adding a touch of warmth. However, if you're communicating in a very formal context or with someone you've never met before, "Regards" may be more appropriate. In any case, it's also a good idea to consider the tone and content of your email when choosing the closing. Make sure it aligns with the overall tone and purpose of your message.