I want to make my life easier and decided to get into text expanders.
I use apple's built in text expander but it has severe limitations. then I found my two favorite apps , alfred and btt, both have that feature baked in
which of the two should I use ? have you ever tried both? is there a pros and cons ?
What are the limitations? Do either BTT or Alfred resolve those limitations? Pick the software which solves those limitations and meets your needs 
well it doesnt have : date for example
that's a good advice, but id rather know what they globally can and can't do, before I run into a limitatiton in , say, a year, and have to copy everything over. i dont believer either have an easy export/import format, so having to copy everything can be a chore
Both BTT and Alfred support dates in text expansion. My advice is to keep things as simple and consolidated as possible.
If dates is all you need, you can't go wrong with either 
It might be worth looking into how easy it is to export text expansion configurations in Alfred. In BTT, all configurations are easily exportable.