Both STR + DEX are viable. You may go full str, full dex, or mix str/dex (or even go con, str, dex, spr).
New archer players I suggest 50-100 CON and 30-80 SPR, then dex & str. If you like to go min-max damage you could go higher str. Especially when you start you will have low critical rate, so dex will not boost your damage a lot.
If you are ranger3 + rogue1 with Feint & Barrage combo, 80-120 dex is ok to barrage faster. Barrage 15 is a must on ranger + rogue builds. The special interaction (mentioned in second post) is very strong and doubles barrage damage. Left click images to enlarge.
You could take barrage 15 on other builds too, but if you dislike barrage, you may opt for this skill distribution:
This example shows ranger3 + appraiser.
The falconer3 + hackapel2 skill points do not change for any build.