pop 110/995, imap 143/993 ?

[voytek at sbt.net.au]

just setting a new Dovecot server to migrate from older system, but, I
have a general question:

1. I've set the server with self issued cert, and both pop/imap
StartTLS/110/143 SSL/993/995 (apologies if I'm using wrong naming
terminology)

is there a 'preferred way'?  should I tell users to use 143 over 993 ? or
993 over 143? or?

my current understanding is that some (MS?) clients might not support
StartTLS/143 ? so best to offer both ?

I think? some public WiFi block 993/995 but allow 143/110, hence, another
advantage for using 143/110

thanks for any advice,

V