Zoom Lens to Replace Kit Lens?

[Hedgehog1]

Alright: Firstly, please keep in mind that I have a grandson in college, a mortgage, a car payment and a spouse who has grown accustomed to eating regularly. Now: I recently purchased an SL-2 with the 18-55mm and the 70-300mm kit lenses. It didn't take very long to figure out that the 70-300mm was not the greatest zoom lens. (Not complaining, as you get what you pay for.) But I would like to improve on the zoom quality somewhat. I would appreciate any recommendations for a better-quality lens to replace my 70-300mm that is in the reasonable price range of, say, $500. I would not object to refurbished. My favorite subject is wildlife, especially birdwatching. Any advice appreciated!

[shadowsports]

@JoeySnaps.  

I agree, the EF 70-300mm f/4-5.6 IS II USM is a great lens.  I got one at release and used it with a T6s.  My control ring has been living on it recently.  Adapted on my R5 C it also does a surprisingly good job.  In its previous life - 6D2, it proved to be one of the best travel lenses I've owned.  I did replace it with an RF 100-400 which is now my casual "travel lens". The 100-400 is actually just a tad shorter and lighter.  You do loose some stops (fully zoomed) f5.6 vs f8 but not bad for what you gain. For real birding, I believe you cannot beat the additional reach a 600mm lens offers in lowering subject distraction and "spook-ability".