White shorts don't instantly make for a good kit, but they can make up for a poor shirt or alternatively they can contribute to a good kit. Nike have so far produced superb home kits in 13/14 & 15/16 and a dull kit in 14/15. In comparison, of the 4 home kits Umbro produced, the first 3 were superb with the third being quite unique. Only the fourth was dull. Ironically enough the last Umbro kit had white shorts but the shirt was terrible. The poor Nike kit of 14/15 had blue shorts on the other hand, with the one time it looked decent coming away against CSKA where, funnily enough, we wore white shorts.
The core formula can be found in the classic core kit used pretty much up until the mid 70s, a core replicated to near perfection in modern terms in the form of the kits of 09/10 & 10/11. Moves away from that formula work with minor alterations such as maroon or navy trims in the collar and sleeves and socks as seen in the late 80s/early 90s. However, Nike & Umbro have both recently made the errors of introducing black in unnecessary places, completely removing white on one occasion and even tampering with the colour code of the badge. Stick to the best formulas and you can't really go wrong. Somehow, these multi-million pound organisations, in tandem with the club's creative departments, manage to do so.