The nice thing about the 1054Z is that the hacks to get full bandwidth and options are well documented, so as long as you don't mind running through some software stuff, you can get a lot more bandwidth out of it (and I think more memory and all decoding options) relatively easily.
The 1104X-E may very well be more expensive, I think it's like $440 on amazon right now. In the same vein as the Rigol, I believe it's software hackable pretty easily to 200MHz bandwidth.
Also worth mentioning (since I managed to miss it the first time), 2 channels isn't really enough to decode SPI. You can get both data channels, sure, but it's much easier when you can get the clock (and the chip select, why not!) on your inputs. Certainly helps in making sure things are being selected right and that the whole system is acting in a way you expect. Alternatively, you could measure a data line or two and a power rail to correlate some reset failure, or an output of a DAC being driven by the SPI line, or whatnot.