Email matters
You can't write off email, it's vital for a lot of people. If you're a freelance or sole trader, it's easy to amass tens of thousands of emails, any of which might need to be retrieved years later in the event of a dispute arising. Storage and backup need careful thought, and proprietary storage systems can make it a nightmare to transfer to a new platform. I started as a sole trader on the cheap with Outlook Express. When I moved to Outlook I discovered (too late!) that in the transfer, the names of senders were retained but their email addresses had been omitted, so it was impossible to write to a former contact. One of several MS email screw-ups over the years, so I now avoid their clients.
Personally I like IMAP with folders in the cloud, so that I can access all recent emails wherever there is internet access. But I hate to be dependent on the internet and my email server working, so I use clients that synchronise the server folders with local ones. The client on my desktop also has separate local folders for archiving.
I'm moderately happy with my setup but as I'm a Vivaldi browser user I'll certainly try their client - after a decent interval. With IMAP it's easy to try a new client so long as you're confident that it won't delete emails in error or screw up your folder system.