Hardware advice for new combined server

Hi there.

I am currently running Openmediavault 5 on an Odroid HC2 (upon which I run TVHeadend and a MYSQL database to record the resume status from various Kodi clients).

I am also running Home Assistant on a RPi 3B+ and also PiHole on a RPi 1B+.

I noted, the other day, that the RAM use on the HC2 was over 89% and I was wondering whether it was time to build a slightly more powerful server and have everything running on that instead.

For power consumptions and small footprint, I was thinking of a RPi 4.

However, I am not thinking of something like an NUC instead (also small, but lots more power for not a huge amount of additional power usage).

Do you think this is a good idea and, if so, what sort of NUC should I be looking at?

I was hoping to run OMV off a USB stick and then run all my programs, via docker, on an SSD drive and then add a 3.5" hard drive for all my storage.