pop 110/995, imap 143/993 ?

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