This is a good question but the answer to this is more trickier. As the way our body acts towards drugs is not defined in a said pattern, the treatment remains a miracle in many cases. My suggestion is go for the one with higher half life but before that know certain answers...1. Does your drug act on surface receptors or inside cellular components?......2. Does your drug attaches to receptors and get carried on or causes cell lysis?.....3. Does your drug travel through blood/intra muscular/oral?......etc,,,,,,to put in a nut shell you must know the target, action, transport and its catabolism. Based on a detail profile only you can decide....but when you ask blind folded, higher half life period is better as your drug might need to survive till it reaches its target.