I have had both.
The Stiletto Deuce (Stage 1) I had first and really liked the clean channel. It was really warm and round sounding. The Dirty channel on tite gain was nice as far as gain but not as full as the dual rec (IMO) it was a bit thin. Great for Classic rock or hair metal but not what i wanted as far as rip ur face off metal.
The Fluid drive would have been great as a lead channel (which is what if was for) but i had to use it as my only distortion channel so it was hard to set it to be crunchy and gain, it was a bit too rounded.
Bear in mind this was my first amp and i was going for a aggressive high gain head. I didn't try a boost or eq. also i was using a prs se custom, not the best pickups
The Rectifier I am not as sold on its cleans yet. I don't like them as much as I liked the Silettos. The Cleans on the recto don't balance well with the distortion setting i run either. i have to run the solo to get them loud enough. The 3 channels is great because i use channel 2 for lead (fat on the single notes with great harmonics and gain) and channel 3 for rythum aggressiveness. I like the distortion better on the Recto for my style.
Conclusion - Stiletto has great cleans and is a great lead head. Can probably hit the high high gain with an od can can have some added fullness with the use of a eq pedal. Great for classic rock, blues, anyting clean oriented or more marshally distortion (EL-34s)
Rectifier has a slightly darker (maybe is the word) clean channel. Great for high gain, great for versatility, can do classic rock as well, has some good pushed clean settings. Good for about any style but better for me for the heavier stuff. More of an aggressive rounded sound (6L6)
All of this is my opinion from my expierence. Bear in mind also i use an ec-1000 with emgs on my dual rec with an od and eq. However, i do like the sound i get without them better for distorion than the stiletto.
Stiletto also was more plug and play, instant gratification, and more mid-ranging, cut real well. The Recto took some work, always tweaking, and sometimes find myself tone shaping more than playing. (may just be a phase)
Honestly it all comes down to style.