Cleric is widely recognized as one of the strongest core-class. And half-elves make good clerics.
Human clerics are also good. I think those two races are the best for clerics. Both of them have no significant weakness. Human has +1 feat and +1 skill/level. HE's low-light vision helps much when they cast offensive spells. Also, bonus to will saves against Enchantments augments the advantage of cleric. Bonuses to social skills synergy well with the selection of cleric class skills.
Elves, while not bad, has low con. And their high Dex does not help much as most clerics wear heavy armor. And again, low con sucks for everyone.
Dwarfs and Half-Orcs are not bad. But they have low CHA. Turn undead is a very important ability by itself. Also, various divine feats favor high CHA cleric.
Gnomes and Halflings. Small size and slow speed are simply no good. Typical clerics wear heavy armor. So their speed is now 15 ft. Too slow. Also, small size is really bad when cleric is meant to do some melee combat.
Saeviomagy said:
??
A half orc gets darkvision and +2 strength. He loses int and chr.
A halfling gets a huge amount of stealth augmentation, -2 strength and a slow speed.
I'm not really seeing how the halfling is worse off.
Those stealth ability is only useful for rogues or ranger types. But in dungeon, dark forest, dark street array and such, the lack or low-light or dark vision makes them less useful reckon/tracker/assassin/whatever.
They are also slower than other races. That is bad when they scout or track something. Also, in melee, slow speed slow speed means that halflings are not good at taking flanking position.
And their small size. In 3.0/3.5e, size category affects on most of the special melee attack options. Halfling rogues who try to fight in melee are often grappled, disarmed or tripped. I know at least 2 halfling rogues died simply because they were small sized (one is swallowed by a large sized monster).
What I am trying to say is, while most of the racial bonuses are good only for Rogue or Ranger types, halflings only make very inefficient rogues or rangers.