Disclaimer: I am the developer of instadub.
Any of the main bots can like posts, it is very basic functionality. The question on which would depend on other features. Such as price, other functions, desktop app, web app, support, program work flow etc
Many people on BHW use jarvee and are happy with it.
Many people use GMT and are happy with it
Many people use instadub and are happy with it
Those are the 3 main ones you will see mentioned on BHW. But other options exist. You will see mentions of followliker although less than you used to, but am sure people are still using it successfully. There are also a few other programs you will see mentioned, but they are either new / smaller. Which can be a good thing. Getting in with a new product means you can usually have the ear of the developer and help shape the direction of the program as it improves. However, the smaller programs, probably have a slightly higher chance of not being around for years to come (some will sure, but some won't)
As for the online / web app options. I don't know so much about them, but you can find them on BHW I imagine with a search.
tbh, for what you want to do, you will happy with any of the above
