I prefer email not only because that way I always know who is sending it but also because it's something I can file away, print, etc. I keep all my business emails- I have business emails going back to 1997 (maybe longer) all sorted in to folders for each of my clients/other business partners/vendors, etc. I also use my inbox as a 'to do' list. Whatever emails are in my inbox are emails I still need to act on in some form. Once I am done with that task then the email gets filed away.
You can do none of that with text messages. Not only that but I access my email from no less than 4 different devices daily. I use IMAP so it's the same data across all devices.
Not to mention the fact that email allows for more than 160 characters so you can actually compose a professional response and not have to resort to using sms shorthand.
Yes, I'm rather anal/OCD about my business communications. All use proper grammar, paragraph structure, greetings, salutations, etc.