Curious what the view is on taking improved DR feats vs taking toughness feats.

Build is a WF 20 Ftr, max str and con. DPS focus, no AC, Kensai THF (Falchion).

I have 5 general feats open in my build (not class feats). I can take Adamantine armor and 4 DR feats, or toughness 5 times, or a combo in between.

The question is whether to max out DR at the expense of HP, or max out HP at the expense of DR, or a blend? Similar question on AP usage (take the DR line all the way, or max out the HP enhancments, or a combo thereof)?

Ultimately, I guess the question is...what's more useful...a 10 DR or 140+ additional HP or something in between?