I've used Glary and Comodo System Clean. Comodo broke one system, but it has a very nice feature where it does not make the changes permanent until you check everything out. I was able to roll back to a working system, with no problems. In any case, these programs do NOT make your computer perform "better than ever" - at best, they can take it back to when it was new. And you should NEVER run these to "fix" a broken computer.
I really only feel comfortable using a good cleaner on a system when I have been using it since the computer was new. If I run a cleaner and it says it has found 800, 1000 or more "errors", I back out as fast as I can. I like to run CCleaner to clean out the clutter immediately after building a new computer and applying all the upgrades. Then I run it after major upgrades, or when changing out major programs (like if I change security scanners).
If a cleaner has never been run on a older system, there is a very good chance something will break when running it. Even with CCleaner.
If you do not know your way around the Registry, or do not know what is happening, then
I recommend just leaving the Registry alone. And ALWAYS backup the Registry before dinking with it. These three programs I mentioned offer to back up first, but I use
ERUNT regularly and highly recommend it. And ALWAYS ensure you have a good backup of all your important data.