First buy from Tracksmith should always be Reggies or Session shorts -- just fantastic form, function and durability. I have session shorts with 500+ wears that basically look the same as when I bought them. I've also had great results from the Fells Tights, which are the most comfy tights I've ever worn.
Tops are more of a gamble. The thinner (twilight/strata) stuff is nice, but thin and gets stretched out with extended use. The heavier garments and tshirts have weird fits -- super boxy and unflattering, especially for a runner's build. Skip the Van Cortland singlets -- they aren't comfortable to race in.
One top that excels is the Brighton base layer; lighter colors hide the pilling better as they age. The rapid transit polos are nice too, especially for travel, but ridiculously expensive.