Sweet!
Is there a good site to see top valued cards for a certain series? For example if I'm buying a pack of Upper Deck 19-20 Series 2, which are the most valuable cards?
I've never bought a price guide so I usually rely on eBay sold listings and COMC (Check Out My Cards, a site that sells singles) listings. They're not always 100% accurate but should provide at least a decent gauge at a card's value. I personally don't know of any site that lists the values of a product's whole checklist, but if there is, I'd be interested to see it!
The big selling point of Series 1 and 2 is always the Young Guns. Series 2 typically has a weaker checklist than Series 1, since the top rookies usually go in the latter; however, this year I personally think the Young Guns crop is stronger in Series 2. Makar is the biggest one but there are also a lot of other sought after names: Suzuki, Dach, Elvis, and Kakko just to name a few. I have pulled each of the first three so far. Series 2 also has canvas Young Gun variants of some big rookies who had their base Young Gun in Series 2, like Quinn Hughes, though these are less common (I think 1:2 boxes). There are also rarer Clear Cut (acetate), Exclusives (#'d to 100), and High Gloss (#'d to 10) variants of each Young Gun. Young Guns aren't the *only* valuable cards in Series 1 and 2, but they are the most common ones what most people buy the product for.
Series 1 or 2 are definitely good products to start with for someone new to the hobby. A box of either won't break the bank and gives a shot at good value. They also come in several formats. You can typically buy a 24-pack hobby box of Series 1 for about $70, Series 2 for $75. A 24-pack retail box of either usually goes for about $20 less. The main difference between the two is that the former offers sets like the Clear Cuts, Exclusives, High Gloss and other insert sets that can't be pulled from retail. Both 24-pack boxes guarantee six Young Guns. There are also retail tins (9 packs, 2 Young Guns) and retail "blaster" boxes (7 packs, 1 Young Gun) that offer an even cheaper buy at about $15 and $25, respectively. It's a fun set to chase and you have a lot of options for how to do so.