OptiLube is great for lubricity IIRC because it is biodiesel based. If you are OK with using a biodiesel blend in your TDI then OptiLube is the way to go.
Howes Lubricator Diesel Treat and PowerService Diesel Fuel Supplement (white bottle) are my 2 favorite additives and I use one or the other with every tankful. My priorities with an additive are to take care of any water I can't avoid getting and to increase lubricity. Providing anti-gel and boosting Cetane levels are of secondary importance. I don't use PowerService Diesel Kleen (silver bottle) because it doesn't do anything for water and doesn't have any anti-gel stuff in it. PS Diesel Kleen is a summer-only formula. I use PS Diesel Fuel Supplement year round to take care of water and add lubricity.
Assuming diesel fuel at the pump has been properly winterized for the region, most gelling problems people report in the dead of winter are actually icing problems due to water from condensation and not actually gelling. People often mistake icing for gelling. They think they have gelling but actually have icing instead. Even with properly winterized fuel, icing due to water from condensation can get you in trouble long before gelling will in the bitter cold. Avoid the water! Fuel up ONLY at high diesel turnover stations along major routes to avoid getting water contaminated fuel from condensation. Go where the big rigs go to fuel up. Avoiding water in diesel fuel is particularly important during winter months in cold areas due to condensation being more of a problem.
Water in diesel fuel from condensation destroys pumps and injectors in no time at all and does so faster than poor lubricity will. Free water in diesel fuel appears to be what kills the HPFP in the CR TDIs instead of poor lubricity. The HPFP in CR diesels are more susceptible to damage from water in diesel fuel compared to older rotary injector pump diesels and VW's PD TDIs but they too will eventually be destroyed. The bottom line is free water in diesel fuel absolutely must be avoided at ALL costs!
Standadyne takes care of water with a demulsifier to help water drop out of diesel fuel so the water separator in the fuel filter can catch it. PowerService Diesel Fuel Supplement (white bottle) controls water with a solubilizer to help keep water completely dissolved and dispersed so that it can pass harmlessly through the system. Howes uses a demulsifier like Stanadyne. I don't know how OptiLube takes care of water. Whatever method an additive uses to control water, it is slugs of free water that absolutely must be prevented from being ingested by the pump and injectors. Which additive you should use depends on how you want to take care of any water you can't avoid getting.