Which is the best pc health software that you use and like the most?

I like Revo and iobit uninstallers and glary utilities pro version.
CCleaner to delete the junk files and clean registry errors.
Hijackthis to check something fishy.

The most important is a good antivirus that doesn't eat up system resources and also provides excellent protection and has a very good firewall that can be configured. I use Bitdefender for that and for some malware that bitdefender does not detect the first time, I use Malwarebytes. But that's not all. If you have a hobby of trying out new softwares, then you must keep your pc clean and somewhat unaffected by the installing and uninstalling of softwares for it to be running like new.
Revo uninstaller is the best of the best uninstallers! It finds and deletes all files and folders and registry entries of any software in seconds. I like it more than others because I have noticed that other uninstallers mess up the registry while deleting the registry items but Revo doesn't.
For the registry files that no uninstaller can remove and to delete empty registry items, I use RegClean Pro. It is a Microsoft Gold Certified software. Very few registry cleaner softwares work well and this is one of the best and most effective. It also defragments the registry making it more quick to access and thereby makes your PC faster.
Other such software I use is Dll Files Fixer. It finds and installs any dll that you want. It also defrags your installed dll files. Its may not seem much but makes a lot of difference.
I recommend 4 Gigs of RAM for Vista and Seven users. Atleast 1.5 GB for Vista and atleast 2 GB for Seven. 3 GB will be adequate but if you have 4 GBs, your PC will never hang. And sometimes that it does due to RAM malfunction can be prevented by SuperRam software. There are many many memory optimising softwares but they are a little too much and in turn of keeping your memory free, they use about 15-20% of your CPU at all times. That's why I recommend having adequate RAM and SuperRam installed.
For faster internet I use cFos speed. There are many small customizations in it but I never touch them. I just keep 'favour ping' on instead of 'favour bandwidth' and my browsing experience has improved greatly. I am getting an extra 10-15 KBps download speed too since I have installed.
These all are very resource conscious and effective softwares. You must also keep your other softwares updated for better overall performance. For this I use a free software called FileHippo Update Checker. It checks the versions of all your softwares and finds their updates and gives their updates' links to you in one web page. You can decide which one to download and upgrade and which one not to.
Lastly, you must always keep a watch on softwares running in the background. Turn off unnecessary softwares that start with windows from their respectice settings or from msconfig altogether. My experience has been having a quite sufficient RAM installed on your PC will keep running like new always. Have both RAM sticks of the same type(1.5 and1.5 OR 2 and 2 GBs) to prevent it from malfunctioning and for greater performance. See that your CPU usage always stays at 15-20% average max when idle. Have a dedicated video card for graphics. That will radically improve your PC's performance and preserve its health.

TuneUpUtilities 2012 can do all the stuffs of Revo Uninstaller, Cc Cleaner etc. Its an All In One package.

I Would recommend Iobit Advanced System Care.

i am using it for past 4 years and i had no trouble at all.
great utility tool with good speed up tools.

trendmicro says IOBIT has hacked its source code and could be one malicious chinese maker.

TuneUpUtilities 2009 Is Best Utilities for Maintain Our PC.

My machine :
Ccleaner : to clean junk files and registry problems .
Avast Antivirus : for virus , trojans etc.

i am with uniblue powersuite and norton internet security .

Ccleaner and Avast

well if we go for free its Microsoft security essentials (this one is free doesn't mean its not good its an awesome antivirus gives you just much more than a free antivirus )
and for paid one Quick heal internet security or nortan internet security they are the best in the business

Quick Heal ? : amazed: