I've often seen requests for help making an airgun purchase from people relatively new to airguns so I'll offer some generic advice. Hopefully other experienced shooters can add to the suggestions.
I used to teach IT (information technology... computer stuff) at the college level and often told my students that it was impossible to know everything (especially in a fast changing subject) so learn to find the specific information you need.
To that end, I'd say you should decide what discipline (start with one

) that interests you most and research that.
So what do you want an airgun for? Casual plinking? Seriously competitions? Pesting/hunting? Target shooting?
Then ask the question on the forum: What do you recommend for *enter your interest here*? You WILL be overwhelmed with suggestions based on personal preferences.
To help manage and focus the recommendations to your needs you should include as many (realistic) considerations/details as you can about your...
- Budget - airgun, scope, accessories. One airgun or do you anticipate buying several?
- Shooting environment - basement, backyard, shooting range, farm
- Particular shooting interests
- How much shooting will you be doing (daily, weekly, monthly? )
... etc
I say be realistic. Your not going to get a Porsche for the price of a VW Beetle, ditto with airguns. As far as performance goes, again be realistic, all the laws of physics apply. Power costs money and resources, get what is appropriate.
My recommendation is to buy what you REALLY need for your application. Don't get sucked in by velocity or power or caliber. There are general purpose airguns and one for very specific uses. Quality comes with a price, I prescribe to the "buy once, cry once" crowd and prefer to save up for the best I can afford. Each to their own.
Hope this helps someone!
Cheers!