using 2 iPhones

I would do the latter.

Keep work and personal separate as you never know when one will interfere with the other if you have both on the same Apple ID.

Since work is paying for the phone they have the right to inspect your device at any time without warning. Which means if there's anything that you'd rather keep personal under your own ID, if you're logged into it on the work device they're going to see it - or a customer might (if you deal with customers).

Just a good idea to keep them apart.

 

^Agreed above. As a person that carries a personal and a work phone that can be FOIA and have a court ordered subpoena slapped on it at any time, go with separate accounts on the phones. Even if that wasn't the case, I would still use separate accounts. Just makes good business and personal sense.

 

I will do one step further. Keep the separate account completely off relationship with all my personal ID. Which means, no family share. If I need a duplicate app purchase, do so, as long as it is not expensive.