Fighter provdes two feats and towershield proificiency. On a mellee cleric, feats are very tight so that is a huge benefit.
The paladin provides:
1 - some additional spell points (divine caster)
2- lay on hands (not needed on cleric build)
3 - better saves, but fort and will are strong on a cleric.
Essentially you are giving up 2 feats for a few SP and +4-6 reflex save. On a halfling with a decent dex, the reflex save may be handy but otherwise it is probably below the useful range anyway at high levels.