As others have pointed out, oscopes with decoding features are typically limited in their decoding ease of use and overall feature set, especially in 'more affordable' gear. A cheap generic decoder running open source Sigrok software usually outperforms this tier of scopes.
Certainly, an oscope is a useful tool and if the logic analyzer fails or spits out garbage, it's handy to inspect the waveform for issues. At that point, the Digilent Analog Discovery starts looking good.
IMO, a $10-$20 investment for a generic LA is a good starting point - you can always move up to better equipment later if you need to. But for that price, why not just get one to see if it does the job ?