If you need instant and short-term results, go for New Account, as Fiverr will give a chance to new sellers also. And in most cases, it might be possible that Fiverr gives new people more weightage if your skills are in trend. However, if you think from a buyer's perspective, the older, the better.
If I were at your place, I would definitely go with the old ones and push harder in optimizing Gigs on a daily basis.