The Helly Hansen Lifa (long sleeve) is arguably the most technical baselayer and perhaps the best performer money can buy
I have bought many other makes including Rapha, Rab, M.E. and with the exception of Paramo, for me Helly Hansen, particularly when cost is considered, wins hands down.
I wear mine for hiking, camping and as a baselayer under my cycling jersey. The LIFA top pushes away sweat superbly, it feels very light and comfortable and lasts for ever.
I only buy Helly Hansen tops for high energy activities and will only reluctantly use another make.