Many of us are fans of Unbound. dnsmasq has served our needs well throughout the project. Is there a specific reason you think it is outdated? And what makes it complex to troubleshoot? It's the same dnsmasq we have always used, but its closely coupled to our software, which should make for easier troubleshooting by removing variables from consumers installation.
We have often discussed giving users the choice of what DNS server to install and/or what Web server, but the unfortunate thing it comes down to is time to develop. We're all volunteers working on this in our free time.
As of now, I don't see dnsmasq going away from Pi-hole since we are very familiar with it and we also have some lines of communication with Simon Kelley, which works to our advantage when developing if we run into questions.
For now, I'd point you to: