MR tuffy works for me. No flats even on a ratty tire. If not installed correclty they can cause flats, they reduce efficiency of the bicycle. Consider picking class out of your tire every 5mi-10mi with a knife. Mr Tuffy stops the glass but it is still embedded in the tire slashing it up.
2000 Montague CX, I do not recommend it, but still ride it.
Strida 3, I recommend it for rides < 10mi wo steep hills.
2006 Rowbike 720 Sport, I recommend it as an exercise bike.
1996 Birdy, Recommend.
Wieleder CARiBIKE (folding), decent frame.