The last few sets I've used have been John Pierce mediums - they seem great, I play every day, and I usually go 6 months between changes. Its been years since I broke a string - I don't think I have since I stopped playing traditional jazz with a flatpick!. Dwight Diller recommends using a second string for your fifth if you do a lot of his sort of double thumbing - but this would be expensive unless you buy your strings individually.

Cheers
Ray