I wouldn't recommend Siemens or Fluke,
there are more specialised vendors like:
Janitza
Bender
Chauvin Arnoux
LEM (with a ?)
Socomec (with a ?)
to name a few that came to my mind in a short time. I'm not associated with any of these, but have some experience in development in such units (the company I've worked for doesn't exist anymore).
The requirements for power quality monitoring are quite special and covered by various standards. From my experience, these are better met by such vendors than the general purpose ones. Fluke once had a meter that would meet these requirements, but afair it was rebranded and I don't know if they still sell it. From what I remember, Janitza has a quite sophisticated logging and data base behind their units, don't know much about the others, so you'll have to get informed by yourself for a comparison.