People complain they don't one or two shot others, then they go str and then complain they are getting ganked all the time.
IMO now with the armor changes, bounces are way less likely to happen thus PS got nerfed a lot. People consider str to be better than agi (over 15/15) because they are used to play rhino tanks that can't disengage. Playing an agi character is totally different from playing an str character, but if people don't know that and don't change the way they play, it's clear str is better for them.
The main thing with high agi is the ability to disengage fights and control a very large zone around you. Projectile dodging is also easier. Furthermore, duelling with an agi oriented character requires another approach. I'd say agi is better for defensive, mentally strong duellers that block very well and will remain calm and constant if the duel becomes long. Str is better for aggressive duellers, with decent blocking but very fast and sophisticated attack shemes. Making elaborate holds/feints/chamberblocks requires more error tolerance from the char and equipment than simply blocking and attacking for hours.
There are other things that differ between str and agi characters. In fact almost everything changes at least slightly, but you got my point already.
this.
also, strength give more advantages (1hp per str point, 1 raw damage per str point, unlock IF and PS)
while agility gives only slightly running speed and no more (since jan patch) 0.5% swing speed per point. (one agility point give something like 1% or 1.5% running speed).
that's why balanced or 21/18 24/15 builds are imo the best bet. they give you decent speed, good damage, good passive defence.
otherwise, agi biased builds (15/24 phyrex-like builds) gives you a lot of mobility even with a 20weight armor, lightning fast blocks, but need good footwork for speed bonus or good aim for head hits to be really effective.
also agi biased builds give you the ability to disengage, fast flank maneuvers, effective bait tactics, ranged evasion, anticav footwork, mobility to go where you need to.
str builds rocks the siege defence. awesome in tight spaces where you can't get speed bonus, where you can take a beating with 85hp and 70 armor, where you can use mallets/great mauls effectively.
also, str builds works best in a tight brawl. when you have some shield cover and you break the enemy line with a hard hitting axeman, you can literally wipe shielders away.
also high STR & max ironflesh builds needs high armor to maximize the armor rating bonus. for instance, a 36/3 build with 95hp and 80ish armor (loomed plate and gauntlets) needs something like 10hits from a 40ish cut weapon with 6-7ps and at least 5 good hits from a bec de corbin / morningstar balanced build (6 ps).