At the time of this post I have a 90 Ochain and 95 Aegis. Currently 3/5 on marrows for 99 Aegis. I built my Aegis the hard way, before neo dyna. Aegis is a solid shield, I eat AM2, Tier V and ja spells for breakfast. And let's not forget to mention the 350+ shield bash. Now Ochain.... it should say 25% of the time it successfully blocks. But when you hit that sweet spot it's great. Blocking like crazy and building TP. Ochain reminds me of Super Mario Bros 3-1, where you get 100 lives by jumping on that turtle at the end. Sometimes you can nail it on the first try, sometimes it's a pain.
To repeat what has been said throughout this post, everything in this game is situational. It's all about pdt vs mdt. When a mnk hundred fists, use Ochain. When you see a thunder V use Aegis.
It's funny when people that have neither think they know everything about the 2 shields.
Bottom line, just build both.