Phonealarm has more features (dare I say too many) but is unstable for many people including myself. I have used various versions over the years (I even purchased the program early on) but will no longer use it because I found it too buggy to be useful. I can't speak to later versions but regardless, I'm done with it.
SPB Phone Suite has some nifty features (picture speed dial, for one) that phonealarm doesn't have. It's also lacking some features (a lot of profile flexibility, lack of skin support) that phonealarm does have. But it has been rock solid stable for me. The repeating alarms and profiles work like a charm--to me that's all I need so I prefer Phone Suite.
You might also look into SBSH Phoneweaver. It has some feature overlap with both of these apps and SBSH makes quality software as well.
I'm sure you'll get some other opinions too
Edit: I might add that it appears more people use phonealarm because it has been around far longer than the other two apps, which came out within a week or two of each other (and about a month ago). Given time I would expect to see those products mature and take a lot of the profile software market.