best drycore transformer to a delta dsecondary service

[rsdk123]

Hi,
I want to benefit from your experience regarding a delta secondary service.
We are upgrading an electrical vault.
On the primary side, we are coming from a 3 phase bank of pole tops 25kv/600v to a dry core 600v/240v to feed a 15kva delta bank service.
I am not sure if we should go with an autotransformer or a delta-delta dry core because we don't want to introduce a neutral to the service.
Any thoughts about that?

Thanks