I'd say the Neopower over the Modstream anyday... the modstream was appropriately named, it's a pared-down modified version of the Powerstream-- It doesn't have the adjustable rails, has less heatsink space (equalling less efficiency) to make up for the 120mm fan. Granted, the Neopower has a 120mm fan as well, but it was designed from the ground up as a unit, not modified from an existing design. Maximum PC put them head to head and the Neopower came out on top... Just my two cents.
They are both excellent PSU's no doubt however... I'd just pick the Neo.