Backing best, hands down unless you have a braid ready spool.Tape if you want, but the 25yards of braid you get over the mono is too little too late and just a little bit lazy. You just lost the battle and had no buffing factor.
The backing is not just about filling your deep spool or even not slipping on the spool (because that can happen fully spooled without as we all know). However as you get nearer the centre of the spool the drag harshens of course and without the dampening affect of the mono "cushion" you are more prone to sudden shock breakage.
As mentioned above, once you see the mono it's probably the chip shop for dinner, you could back with 5lb mono under 30lb braid, in fact that probably is more logical than going heavy however the ideal would be similar line thickness rather than strengths.
Hey, these are all just opinions and none are right unless they make logic for you.