This is some pretty sound advice as well. I bought a Vanguard S1 when they were on sale and put a Timney in it for another $120. It wears me down when walking around with it all day (snowshoeing through thick snow) but boy is it nice to shoot, groups a LOT tighter than my partner's T3 lite that's for sure. As per the caliber choice.223 is unbeatable if you're only going to be shooting bought ammunition for obvious reasons. If you're planning on reloading I believe there are better choices. .204s are flat, fast, cheap, and you can see your hits in your scope even with the lightest of guns. and something like .243 offers you heavier bullets which will buck the wind better for those long shots (or if you decide to take down a dear)...
...in the end, it's really preference, but I'm sure you've picked up on that by now. People are naturally going to vote for what they've experienced success with. Which in modern shooting tech is almost anything. As such, you'll be happy with almost everything you take the time to get used to and play around with. It's pretty obvious what I'm biased towards
Great point though. I think that if you try to find "one gun" to do everything, chances are...you'll be making some compromise at one end of the spectrum. .243 IS about the minimum for deer, but overkill for groundhogs and more than what's req. for coyotes. Other factors~the report of a .243 is significantly louder than .223 and if you're like most of us...you'll be varmint-hunting on someone else's property and often, near or around their own animals. The gun's report is a factor. Lastly, if you like to see the bullet's impact through the scope, forget .243. It's not punishing recoil at all, but enough of a push that you'll be looking at something else after you hit the go button. To me, a good deal of the fun of varmint hunting is seeing the impact or at least, seeing where the bullet went if you missed. 
