For us it is the 2% back in Disney gift cards for money I'm going to be spending anyhow. Between the ABD trips,
DCL getaways, DVC dues, special events and APs the 2% really adds up.
Welcome to the travel hacking hobby. If I were you, I'd still get the CSR at least for the bonus. You can transfer those 50,000 UR points to SW or use them to purchase travel at 1.5 or transfer them to your CSP account before closing or product changing your CSR next year and save them for your Europe trip. Lots of things will trigger the travel credit including tolls. After the $300 travel credit is triggered, the card is $150 and you are getting $750 worth of travel buying power for $150. Heck, even if you never triggered the travel credit, I'd still trade $450 for $750 any day. After a year, I'd ask to product change that CSR to a Freedom Unlimited.
The rule of thumb when starting out is get your Chase cards first.
If you are looking for cash back the best no fee cash back card is the Citi double cash since it is effectively a 2% cash back on everything with no cap. Unfortunately, it doesn't have a sign up bonus. Barclay Arrival Plus does though and I believe it is current;y at $500+.