WSPR 2 against 15

Hallo everybody !
I´m new here and have the following question:

Have an allmost unused contest-style-station.
For usage in wasted time of unusing think about WSPR should be installed there and work.

Now need some suggestions what to do:
Use WSPR-2 or WSPR-15 ?
Think to use 20 or 40W out for a time of 2 or 4 weeks.

What do you think ?

73 de Ralf / DL3JJ