So which base layer is going to suit my needs best?
Broadly speaking baselayers fall into two distinct groups: Synthetic Fibres, or Natural Fibres.
Produced from petrochemical sourced yarns, such as polyester, polypropelene and polyimide.
For - In general they tend to wick moisture away from the body quicker than natural fibres, and dry quickly.
Against - Without additional treatment they can tend to suffer from odour relatively quickly - however, treatments such as silver ions can help reduce this problem.
At Action Outdoors we offer synthetic baselayers from Paramo and Tilley.
The yarns in this group are derived from natural sources, with Merino Wool being the main fibre used.
For - Merino in particular is more resistant to odour, so may be more suitable on longer trips with limited washing facilities.
Against - Merino tends not to wick as well as synthetics, but it does have a bigger capacity to absorb moisture. It also tends to dry more slowly, but does retain its insulating properties better when wet than synthetics.
We currently use Keela for our Merino baselayers.