At the bottom of the draconic order there's the whites, starting out at CR 2 and 3 RHD. Paradoxially, this makes them one of the most attractive PC's.
Breath weapon is a cone of cold, skills are Swim (somewhat useful) as well as Hide and Move Silently (especially good on the Tiny wyrmling). In addition, white dragons gain fly, burrow and swim speeds, with all very high.
Going to echo the playground here and say these are (finally!) worth +1 LA. Ability-wise, things aren't that interesting, but the speed and general true dragon shenanigans are definitely worth the slight loss in damage compared to a regular rogue type.
These are basically blue wyrmlings with better mobility but worse mental stats, AC and damage. -0 LA again.
Another easy blue dragon comparison, another clear loss. -0 LA.
White dragons gain new abilities at an even slower pace than other dragons (though I must admit Freezing Fog is a nice control ability), so it should be obvious that more HD don't warrant a higher LA.
With this, the chromatics are done (woo-hoo), and I'll soon be moving on to metallic dragons.